Self-study
Trust, which cannot be sustained in the absence of mutual respect, is essential to any long-lasting relationship, personal or professional. ████████ ████████ ██████████████ ████ ██ ████████ ██ ███████████ ████████████ ███████ ███████ █████████ ██ █ ████████ ████████████ ██ ██ ███████ ██ ████ ██ █████████ ██ ███ ████ ███████ ██ ██████ ███████ ███ █████████
Summary
Trust requires mutual respect. Moreover, long-lasting relationships (whether personal or professional) require trust. Personal relationships, such as marriage or friendship, additionally require natural affinity. Long-lasting personal relationships require both mutual respect and affinity. 
Notable Valid Inferences
There are various conclusions we can draw from the conditional statements presented. For example, a long-lasting personal relationship requires natural affinity and mutual respect. And a long-lasting professional relationship requires mutual respect.
8.
If the statements above are █████ ████ █████ ███ ██ ███ █████████ ████ ████ ██ █████
a
A friendship supported ██████ ██ █████ ███ ██████ ███████ ████ ███ ██ █████████████
Must be true. As shown below, a long-lasting personal relationship requires natural affinity in addition to trust and mutual respect. So if the relationship is supported only by trust and mutual respect, without natural affinity, it cannot be a long-lasting personal relationship.
b
In the context ██ ███ ████████████ █████████████ ██████ ███████ ███████████ ██████
Could be false. This answer choice confuses sufficiency for necessity. We know that mutual respect is a necessary condition for trust. But (B) states that mutual respect is sufficient for trust. (“X presupposes Y” means X is sufficient for Y.)
c
If a personal ████████████ ██ █████████ ██ ██████ ███████ ███ █████████ ██ ████ ████ █ ████ █████
Could be false. This answer choice confuses sufficiency for necessity. We know that mutual respect and affinity are necessary conditions for a personal relationship to be long-lasting. But this doesn't imply that having both natural affinity and mutual respect is sufficient for a personal relationship to be long-lasting.
d
Personal relationships, such ██ ████████ ██ ███████████ ███ ██████████████ ████ ████████████ ██████████████
Could be false. The stimulus tells us several necessary conditions for these relationships to be long-lasting, but we don't get information supporting a comparison of which kind of relationship lasts longer.
e
Basing a marriage ██ █ ███████ ████████ ████ ██████ ████ ██ ████ ███████
Could be false. The stimulus tells us that marriage requires both natural affinity and mutual respect in order to be long-lasting. A marriage based on natural affinity will not be long-lasting if it's not accompanied by mutual respect. In addition, we don't know that natural affinity or mutual respect can ever ensure a long-lasting marriage; we know those qualities are necessary for a long-lasting personal relationship, but this doesn't imply that they are sufficient.