Question

read the paragraph. then, add the best topic sentence.
these artists first melt glass pieces in a hot furnace. they then gather the liquid glass onto the end of a steel pipe, called a blowpipe. once the glass cools a little, it is rolled into a round or oval shape. next, glassblowers blow into the blowpipe to send air into the glass, making it hollow. the glass is reheated, blown larger, and reshaped many times to form beautiful glass vases and bowls.
glassblowers use heat and air to shape glass.
people who work with hot objects need to protect themselves from heat.
heat is used in creating many types of artwork and objects.

Explanation:

The paragraph details the process of glass - blowing, which involves using heat to melt glass and air to shape it into vases and bowls. The first option directly relates to the content of the paragraph. The second option about protection from heat is not the main focus. The third option is too general as it doesn't specifically mention glassblowing.

Answer:

Glassblowers use heat and air to shape glass.