Question

read the passage. then answer the question below.
a dock in the red sea in egypt provides a place for boats to tie up. it is also a habitat for many marine organisms. small silverside fish shelter in the shadows below the dock, hiding from larger fish.
seaweed and invertebrates, such as corals and sponges, grow on the wooden posts that support the dock. sponges are filter feeders. they feed by filtering microscopic algae and small animals out of the salt water.
beneath a boat dock in the red sea, the silversides, the sponges, and the salt water make up which of the following? select all that apply.
a population
part of a community
part of an ecosystem

Explanation:

1. Population: A population is a group of individuals of the same species in a given area. Here, silversides (one species), sponges (another species) are different species, and salt water is not a species. So they don't form a single population. The initial check on "a population" is incorrect.
2. Community: A community consists of all the different populations (species) in a given area. Silversides (a population), sponges (another population), and other organisms (implied, like corals, seaweed) along with their interactions form a community. So the silversides and sponges are part of a community.
3. Ecosystem: An ecosystem includes all the living (biotic) components (community) and non - living (abiotic) components (like salt water, the dock structure, etc.) in a given area. The silversides (biotic), sponges (biotic), and salt water (abiotic) are part of the ecosystem of the dock area in the Red Sea.

Answer:

• part of a community
• part of an ecosystem

(Note: The "a population" option is incorrect because a population is a single species group, and here we have multiple species (silversides, sponges) and an abiotic factor (salt water).)