In this task, you are given a multiple-choice question and you have to pick the correct option. Answer with option indexes (i.e., "A", "B", "C", and "D").

An echo is produced by what type of reflection of sound source? (A) Direct (B) Distant (C) Varied (D) Single
D

What is the source of cooling that turns lava into land? (A) seawater (B) refrigerators (C) air conditioning (D) glaciers
A

A hatched chick will know how to construct a nest when it needs to because it is (A) instinctual (B) considerate (C) learned (D) a given

A