Question

read the passage. there are several questions about this passage.
stinkiest place—the rotten egg of io
1
what makes a place stinky? it is quite subjective, really. many scientists believe that smells warn us of potentially harmful chemicals—bad smells indicate things that are bad for us (although this theory does not explain why humans eat liver and onions). however, many things stinky to humans are beneficial to other living things. rats inhabit putrid trash bins, some bacteria eat methane, and flies like poop. so, we have taken a distinctly human perspective to determine the stinkiest place in the solar system. it’s really no contest—jupiter’s moon io produces the biggest stink of all.
2
this is not to say that the solar system lacks stinky places. earth has its fair share—boggy marshes, geothermal areas, landfills, and pig sties, to name a few. new zealand’s 55 million sheep and cattle produce about 90% of the country’s methane emissions (kiwi farmers have fervently opposed a “fatuence” tax), indonesia is home to the exotic and popular durian, a fruit with such an offensive odor that it is banned in singapore hotels and subways. on venus, corrosive clouds of sulfuric acid completely envelop the planet, producing an acid funk of global proportions. hydrocarbons on saturn’s moon titan fall as toxic precipitation, pool in lakes and streams on the surface, and seep into the underlying goopy soil. titan smells like one big oil refinery.
3
but jupiter’s moon io smells like a jumbo rotten egg. hydrogen sulfide produces the characteristic rotten egg stench, and the stinky compound has been observed both on io’s surface and in the upper atmosphere. in fact, the sheer abundance of sulfur compounds creates the moon’s distinctive red and yellow coloration.
4
during explosive volcanic eruptions—spectacular events that are quite common on io—sulfur gas launches high into the atmosphere. although the mechanism is not completely understood, photochemistry decomposes some of this sulfur gas and forms sulfur dioxide, hydrogen sulfide, and other sulfuric compounds. sulfur molecules freeze on the surface to form red patches near volcano vents. eventually, the red frost turns yellow as sulfur molecules react to form stable sulfur rings.
how do paragraphs 4–8 help develop the ideas in the passage?

1. paragraph 4 explains that scientists have much to learn about io, and paragraphs 5–8 explain the topics scientists will study,
2. paragraph 4 describes the colors of the sulfur on io, and paragraphs 5–8 describe the reasons that the colors are permanent.
3. paragraph 4 explains that the sulfur on io comes from volcanoes, and paragraphs 5–8 explain why io has so many volcanoes.
4. paragraph 4 describes several sulfur compounds, and paragraphs 5–8 describe how these compounds are changed by io’s orbit.

Explanation:

To solve this, we analyze each option:

• Option 1: Paragraph 4 is about sulfur on Io's volcanoes, not what scientists will study. Eliminate.
• Option 2: Paragraph 4 focuses on sulfur from volcanoes and its changes, not just colors. Eliminate.
• Option 3: Paragraph 4 explains sulfur comes from Io's volcanic eruptions. Paragraphs 5 - 8 (though 5 - 8 aren't fully shown, from the context of Io's volcanoes and sulfur) would explain why Io has many volcanoes (as Io's volcanic activity is key to its sulfur and smell). This matches the development.
• Option 4: Paragraph 4 is about sulfur from volcanoes, not "several sulfur compounds" in a general sense, and the orbit - related change isn't supported. Eliminate.

Answer:

1. Paragraph 4 explains that the sulfur on Io comes from volcanoes, and paragraphs 5 - 8 explain why Io has so many volcanoes.