Correct Option: D

In the courtyard of the Quwwat-ul-Isalam mosque of Delhi stands the famous iron pillar in the memory of Chandragupta II. The height of the pillar, from the top of its capital to the bottom of its base, is 7.21 m (23.7 ft), 1.12 m (3 ft 8 in) of which is below ground. Its bell pattern capital is 1.07 m (3 ft 6 in) in height, and its bulb-shaped base is 0.71 m (2 ft 4 in ) high. The base rests on a grid of iron bars soldered with lead into the upper layer of the dressed stone pavement. The pillar's lower diameter is 420 mm (17 in), and its upper diameter 306 mm (12.0 in). It is estimated to weigh more than six tons.