Given a scientific passage and an answer, generate a question for the given answer.

Ex Input:
Passage: Acidity is measured on a pH scale. Rain that is 5.0 or less on that scale is considered acid rain. Answer: ph scale

Ex Output:
Acidity is measured on what kind of scale?

Ex Input:
Passage: Athletics are very competitive these days at all levels, from school sports to the pros. Everybody is looking for that edge that will make them faster, stronger, more physically fit. One approach taken by many athletes is the use of amino acid supplements. The theory is that the increase in amino acids in the diet will lead to increased protein for muscles. However, the only real benefit comes to the people who make and sell the pills. Studies have not showed any advantage obtained by the athletes themselves. You're much better off just maintaining a healthy diet. Answer: a healthy diet

Ex Output:
Which is the best way to maintain a strong, fit body?

Ex Input:
Passage: The binding of complementary bases allows DNA molecules to take their well-known shape, called a double helix . Figure below shows how two chains of nucleotides form a DNA double helix. A simplified double helix is illustrated in Figure below . It shows more clearly how the two chains are intertwined. The double helix shape forms naturally and is very strong. Being intertwined, the two chains are difficult to break apart. This is important given the fundamental role of DNA in all living organisms. Answer: double helix

Ex Output:
The binding of complementary bases allows dna molecules to take their well-known shape, called a what?