Explanation:
Habitat for Humanity is an informal group, because the organization came naturally into society. The group came about due to a large number of people wanting to volunteer that all share the same goal for the group. One of that biggest challenges that Habitat for Humanity might face would be the rising construction and material cost combined with a lack in funding for their projects.
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.
It would be best to have a context for this question, but from what I can see the best answer is the last one: that relationships require regular maintenance. All the other options are not very helpful advice about how to have a healthy relationship.