TASK DEFINITION: In this task, you're given an open-domain question. Your task is to provide an answer to the given question. There is only one unique answer for each question. Your answer should be short, and refer to an entity, date, number, etc. Do not put your answer in the context of a sentence.
PROBLEM: Who has the most atp masters 1000 titles?

SOLUTION: Rafael Nadal

PROBLEM: What state became a state as a result of the compromise of 1850?

SOLUTION: California

PROBLEM: What does barium do in a ct scan?

SOLUTION:
better visualization of the gastrointestinal tract