Which action is described by the verb "reduce"?

The verb "reduce" specifically means to lower in amount, degree, or size. It refers to the action of lessening or making something smaller or narrower. In the context of this question, choosing the option that defines "to narrow or lessen something" aligns perfectly with the definition of "reduce", making it the most appropriate choice.

The other options do not capture this meaning: one suggests an increase in complexity, which is the opposite of reducing; another implies a complete transformation, which doesn't relate to the idea of making something less; and the last option about adapting suggests a change in response to conditions rather than a reduction in size or amount.