The correct answer is:
(Choice D) The curved surface is a concave meniscus which has formed because of capillary action.
In a graduated cylinder, water typically forms a concave meniscus due to capillary action. This occurs because water molecules are attracted to the glass of the cylinder (adhesion) more strongly than they are to each other (cohesion), causing the water to curve upwards at the edges and create a meniscus that is concave in shape.