The atmosphere in that desolate place looked ominous.

pleasant
encouraging
auspicious
favorable

The correct answer is: ominous.

Ominous means giving the impression that something bad or unpleasant is going to happen. In the context of the question, the desolate place is described as having an ominous atmosphere. This suggests that the place is dangerous or threatening.

The other options are not correct because they do not convey the sense of danger or threat that is present in the question.

Pleasant means giving a feeling of enjoyment or satisfaction. Encouraging means giving someone confidence or hope. Auspicious means giving a good omen or sign. Favorable means likely to be successful or beneficial.