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.

Peptide bonds in proteins can be broken down by the enzyme peptidase. Adrian orders a hamburger and French fries for lunch. He adds cheese and mayonnaise to his hamburger, and then sits down to eat lunch with his friends. Which structure would most likely result from the action of peptidase in Adrian's small intestine?  
 (A) lipid (B) glucose (C) amino acid (D) hydrocarbon
C

When do mutations help make an ecosystem more sustainable?  
 (A) when mutations decrease the number of individuals in an ecosystem (B) when mutations increase the number of individuals in an ecosystem (C) when mutations decrease the number of species in an ecosystem (D) when mutations increase the number of species in an ecosystem
D

Which of the following is the best example of a part of the propulsion system of a tractor?  
 (A) engine (B) front headlight (C) hood (D) steering wheel

A