The answer for the question is definening
Believing that <u>every problem has a solution</u> is part of this <u>set of values</u> a. efficiency and practicality. The definition of the set of values is a main part of the question.
I think the phrase to be filled into the gaps is "the great wall", and more specifically, "The Great Wall of China".
The earlier structures were were built as early as 7th century BC, and they were joined around 3rd century BCE.