The diagram below represents,

A. Simple barometer
B. Fortin barometer
C. Aneroid barometer
D. None of the above

Hint: A barometer is basically a device which is helpful in measuring the air pressure in a particular surrounding. The tendency of the pressure can forecast smaller variation in the weather. These kinds of measurements of air pressure will be helpful within the surface weather analysis to determine the surface troughs, pressure systems and frontal boundaries. This will help you in solving this question.

Complete answer:
An aneroid barometer is defined as a device which is helpful for the determination of pressure by a process that does not involve liquid. The aneroid barometer is a small metal box referred to as an aneroid cell or capsule, which is produced from an alloy including beryllium and copper. The evacuated capsule is opposed from collapsing by a strong spring. The little variation in external air pressure will result in the cell in order to expand or contract. This contraction and expansion will move the mechanical levers such that the small motion of the capsule is enhanced and shown on the front surface of the aneroid barometer. This aneroid barometer includes a pointer, spindle, lever and also a vacuum chamber. Therefore the figure represented in the question is that of an android barometer.

It is given as option C.

Note:
There are two types of barometers. One is a mercury barometer and the other is aneroid barometer. Fortin barometers are the barometers which use a moveable displacement mercury cistern, usually made with a thumbscrew pressing on a leather diaphragm bottom. This will be helpful in compensating for the displacement of mercury in the column with a differing pressure. It is a portable mercury barometer in short.