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.

Which of the following is true regarding the properties of an air mass?
(A) An air mass is warmer at the leading edge and cooler at the trailing edge. (B) An air mass has similar temperature and moisture properties throughout it. (C) An air mass is cooler near the edges and has greater moisture near the center. (D) An air mass has greater moisture near the edges and is cooler near the center.
B