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.
Q: A thermometer shows that the outside air temperature is colder than the temperature at which water turns to ice. However, ice on the sidewalk melts. What probably caused this?
(A) The air heating the sidewalk (B) The sidewalk reflecting sunlight into the air (C) The wind causing the ice on the sidewalk to melt (D) The sunlight making the sidewalk warmer than the air
A:
D