Question

use context clues to help determine the meaning of the underlined word. knowing that number 1 was optional, stacie omitted, or left it out, from her answer sheet. upped increased left it out added

Explanation:

The phrase "or left it out" is a context clue that directly defines the underlined word "omitted". In language - based problems like this, using such explicit context clues (in this case, an appositive phrase) helps determine the meaning.

Answer:

Left it out