it is defined as looking for information by asking various questions about the thing you are curious about?

Inquiry.

Explanation:

Inquiry can be defined as the process (act) of looking for information by asking various questions about the thing you are curious about.

Simply stated, an inquiry is an act that typically involves seeking information by asking questions with respect to the thing you have curiosity for or the thing you wish to know more about.

This ultimately implies that, an inquiry deals with the urge to find information, seek for the truth or knowledge, examine principles and facts about the thing you are curious about.

plasma - state of matter made up of electrically charged particles

the correct answer would be b) volume versus temperature, because they are also directly proportional.