Read the sentence.

a downturn in my weekly budgetary conditions prevents my attending the cinema with you this weekend.

the sentence is an example of

irony
euphemism
inflated language
understatement

This sentence is an example of Inflated language. The right answer is the third one.

Inflated language means language that isn't straightforward and that is often overloaded with confusing terms without much apparent reason for having them.

In this particular case, there are lots of easier ways of saying that we won't be able to go to the cinema this weekend because we don't have enough money, there is no need to use words or phrases such as downturn, weekly budgetary conditions, prevents and attending.