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.

What is the primary function of white blood cells in humans?  
 (A) carry oxygen (B) fight disease (C) grow tissues (D) remove waste
B

When would the highest tides occur along the Texas coast?  
 (A) at sunrise (B) at sunset (C) during a full moon (D) during a half moon
C

Which of the following involves a learned behavior?  
 (A) laying eggs to reproduce (B) having hollow, light-weight bones (C) avoiding insects that taste bad (D) having white feathers on the throat

C