The inner scale of a protractor is read from:

Given:

The inner scale of the protractor.

The circular edge of a protractor has two scales - inner scale and outer scale. The outer scale is marked from $0° \mathrm{to} 180°$ in the clockwise direction (left to right) and the inner scale is marked from $0° \mathrm{to} 180°$ in the anti-clockwise direction (right to left).

Hence, option A is correct.