The correct answer is: D. their elasticity cannot be compared.
The elasticity of demand is a measure of how responsive consumers are to changes in price. A demand curve that is more elastic means that consumers are more responsive to changes in price, and a demand curve that is less elastic means that consumers are less responsive to changes in price.
If two demand curves intersect, then the two curves must have different elasticities at the point of intersection. This is because the two curves must have different slopes, and the slope of a demand curve is a measure of its elasticity.
Therefore, the elasticity of demand cannot be compared at the point of intersection of two demand curves.