You are given a short paragraph, a question and two choices to answer from. Choose the correct answer based on the paragraph and write the answer(not the key).

Paragraph: A fluid exerts pressure in all directions, but the pressure is greater at greater depth.
 Question: We are designing a submarine to study fish that live far below the surface of the ocean. Before we can send a human researcher down in the submarine, we have to be sure it can tolerate the pressure of the water without cracking. The tougher test will be to send our submarine down to 
 Choices: A)500 feet or 
B)1500 feet?
1500 feet?