Correct Answer (2) an element and a compound

Why:

A pure substance is defined as a substance with constant composition.  It can be classified as an element or a compound.  An element is a substance that can not be separated into two or more substances by ordinary chemical reactions.   A compound is a substance that contains two or more elements, but a pure compound's composition will be invariant regardless of the way it was prepared.  A mixture is the combining of dissimilar substances that do not combine to form a compound.  A solution is combining substances into a mixture with uniform concentration (homogeneous) and has a variable composition.

Answering this question:

The best way to answer this question is to know what; an element, mixture, solution, and compound are and find the best combination in the answer. We know an element is about the purest form of substance we've studied.  It is uncombined with anything and therefore we can narrow our choices to (1) and (2).  Between a mixture and a compound we may have to guess a little more, but inherently a mixture sounds impure with two substances put together.  A compound is two substances combined as well but they are actually bonded and form something new. Whereas the mixture is two or more substances combined, but each substance retains its own identity.  So (2) is the best possible answer.