You will be given a definition of a task first, then some input of the task.
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.

Just under half the oil that enters ocean water comes from natural oil seeps on the ocean floor. Just over half the oil in the oceans comes from human activities. Which human activity contributes the most oil to the oceans?
(A) transporting oil over the ocean surface (B) drilling for oil on the ocean floor (C) polluting land with oil that reaches the oceans in runoff (D) polluting air with oil that reaches the ocean in precipitation
Output:
A