Watch : Time :: Barometer : ?

The correct answer is Pressure.

Explanation:

This question is based on an analogy that connects a measuring instrument to the physical quantity it measures.

1. Analyze the first pair (Watch : Time):
A Watch is an instrument specifically designed to measure Time.

2. Apply the same relationship to the second pair (Barometer : ?):
A Barometer is a scientific instrument used to measure atmospheric Pressure.

Therefore, following the logical relationship of [Instrument : Quantity Measured], Barometer corresponds to Pressure.