It is difficult to believe what he tells us because his account of any event is always full of . . . . . . . of all sorts.

The correct answer is A. discrepancies.

A discrepancy is a difference or disagreement between two or more things. In this case, the speaker is saying that the person they are talking about often gives different accounts of the same event. This suggests that the person is not always truthful or reliable.

The other options are not as good fits for the sentence.

• Differences could refer to any type of difference, not just differences in accounts of the same event.
• Discretions could refer to carefulness or caution, but it does not make sense to say that someone’s account of an event is full of carefulness.
• Distinctions could refer to differences or similarities between two things, but it does not make sense to say that someone’s account of an event is full of differences or similarities.