We are given the following conditional:
- Expectation that telling truth may result in physical/emotional harm to others
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Lying is morally correct
The right answer will have as many of these elements as possible.
(A) We don't care about losing the good; we care about avoiding the bad. Eliminate.
(B) "In order to avoid a discussion" does not match anything about physical/emotional harm. Eliminate.
(C) Close! This would have been right if the husband lied by making up a b.s. excuse ("but, honey, I have an appointment to buy a wild mongoose!"). However, the husband lied out of the truth's inconvenience, not to avoid distress regarding his chest pains. Eliminate.
(D) The mother lies ("I love you the same amount") but we aren't exactly sure why she lies. However, I think it is reasonably to assume that telling the truth here ("I love your sister more than you! Mwahaha!") would cause the young boy emotional distress. This is correct.
(E) Close! However, the emotional/physical distress would not be inflicted upon OTHERS by telling the truth; it will be inflicted upon HIMSELF. This is very close but not exactly in accordance with the principle stated.