In a gear train with two gears, the gear ratio is defined as follows
where

is the angular velocity of the input gear while

is the angular velocity of the output gear.
This can be rewritten as a function of the number of teeth of the gears. In fact, the angular velocity of a gear is inversely proportional to the radius r of the gear:

But the radius is proportional to the number of teeth N of the gear. Therefore we can rewrite the gear ratio also as
Answer: Parietal
Explanation: The parietal lobe is where the primary somatosensory cortex is located. This cortex is where all tactile stimulation is processed in the brain and allows to you detect/feel someone scratching your back.
S.I. Unit of mass is Kilogram which is denoted by Kg
In short, Your Answer would be Option C
Hope this helps!