Precision
FoundationWord-choice questions have no grammatical fault in them. Every option parses, so the test is which word carries the most of what the sentence is trying to say.
Years of drought had depleted the district's reserves.
'depleted' names how they shrank
Years of drought had reduced the district's reserves.
correct, and says less
Where it bites
When two options are both defensible. The one that could be used in more sentences is usually the weaker answer, because precision is what is being tested.