How does one recognize a periodic trend on the periodic table?
a. compare an element's properties to the properties of a noble gas.
b. look for predictable changes and patterns.
c. find elements in random positions of the periodic table.
d. look for all elements with two electrons in any orbital.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.