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").

[EX Q]: An object converts electrical energy into sound on a (A) iphone (B) soft carpet (C) outside wall (D) wooden table
[EX A]: A

[EX Q]: Coal and oil directly removed from the ground are (A) directly consumed (B) thrown away (C) made into products (D) stored underground
[EX A]: C

[EX Q]: Each of the moon's phases usually occurs once per (A) week (B) day (C) 30 days (D) year
[EX A]:
C