You are given a science question (easy-level) and four answer options (associated with "A", "B", "C", "D"). Your task is to find the correct answer based on scientific facts, knowledge, and reasoning. Do not generate anything else apart from one of the following characters: 'A', 'B, 'C', 'D'. There is only one correct answer for each question.

At a weightlifting competition, two competitors lifted the same weight to the same height. The second competitor accomplished the lift 2 seconds faster than the first competitor. This demonstrated that the second competitor had more  
 (A) energy than the first. (B) inertia than the first. (C) power than the first. (D) work than the first.
C

Why are some rocks smoother and rounder than others?  
 (A) They have the shapes of the minerals from which they are made. (B) They were smoothed by the action of wind and water. (C) They were squeezed up through the soil. (D) They hardened in rounded pockets of soil.
B

Which scientist is credited for the development of the polio vaccine?  
 (A) Jonas Salk (B) Neil Armstrong (C) Albert Einstein (D) Jacques Cousteau

A