Apositive ion may be formed when a
a. non-metal atoms gains enough electrons to complete its outer shell
b. metal atoms gains enough electrons to complete its outer shell
c. metal atom loses it's outer shell

the answer is na (sodium)

give me abc and i will get it for u.

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.