Believing that every problem has a solution is part of which set of values?

Option a is correct.

Explanation:

According to one of the definitions given for Practicality by the Cambridge English Dictionary, Practicality can be defined as; '' the quality of being able to provide effective solutions to problems:''. When you believe that every problem has a solution, you take it to the practical aspect and you try to solve the problem, that is called Practicality.

And the efficiency part, when one makes good use of everything he or she has to give something of high quality, when one believes that every problem has a solution, the person hold efficiency and practicality values so dearly.