Because he did not want to appear_______, the junior executive refused to dispute the board's decision, in spite of his belief that the decision would impair employee morale.

'Solicitious' (showing care, attention, or concern) in (3) and 'allegiant' (keeping faith) in (5) can be ruled out because they're positive words. As the clue is 'refused to dispute', therefore 'irresolute' (wavering in decision, purpose, or opinion; indecisive) in (2) would not fit our prediction, hence is ruled out. For the same reason, 'overzealous' in (4) is also ruled out. Hence, 'contentious' (always ready to argue, quarrelsome) in (1) fits our prediction, hence is the answer.