Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

Stringed instruments can help show the relationship between tension and frequencies in strings.
Stringed instruments can help show the relationship between tension and what in strings?

The majority of human genes have two or more possible alleles.
How many possible alleles do the majority of human genes have?

The embryo develops in a plant inside the female plant after fertilization.
Where does the embryo develop in a plant?