Marriages where one spouse's energy levels differ markedly f

This is “cause and effect” question.
The form is
Both A and B exist.
Conclusion: A makes B happen.
Assumption: B does not make A happen. (The reverse relationship is wrong)

ANALYZE THE STIMULUS:

Fact: Marriages where one spouse's energy levels differ markedly from those of the other spouse ==> have more fights and fewer friendly conversations with each other as compared to marriages where both spouses exhibit similar energy levels.
Conclusion: mismatched energy levels can seriously threaten the viability of a marriage

Assumption: unhappy marriages do not make couples have different energy levels.

ANALYZE EACH OPTION:

a)Fights that can threaten a marriage are occasionally seen even between couples where both spouses have similar energy levels.
Wrong. TEMPTING but it does not weaken the conclusion. For example, couples having same energy levels some time have fight, but other couples having different energy levels always have fight that threaten marriages. Thus, conclusion is still valid.

b)People’s energy levels fluctuate with seasons and times of day
Wrong. Out of scope. Nothing about “seasons and times of day”.

c)Spouses with energy levels significantly different from those of their spouses usually fight very infrequently with coworkers.
Wrong. Out of scope. Nothing about “coworkers”.

d)It was discovered that people in unhappy marriages assume different energy levels from their spouses as a passive-aggressive way of showing dissatisfaction.
Correct. D shows that unhappy marriages lead to different energy levels. Hence, D weakens the conclusion that different energy levels lead to unhappy marriages. (apply the cause and effect logic above).

e)Energy levels can be moderated and even changed easily by most people, as shown by another study.
Wrong. Out of scope. We do not talk about how energy levels changed by people. We need to focus on the relationshiop “energy levels – unhappy marriages”.

Hope it helps.