Answer: d. elastic section of the demand curve.
Step-by-step explanation:
When using a linear demand curve, it has been found that the top half of the curve represents the elastic section which is where the section A to B cover so this is the elastic section.
The mid point which is B here is the unitary elastic portion of the curve and the bottom half of point B to C is the inelastic section.
In the elastic section, increasing the price by a certain percentage would cause the quantity demanded to fall by a higher percentage than the percentage increase in price.