Task: Question Answering
Input (English): Problem: a cylindrical bucket of height 36 cm and radius 21 cm is filled with sand. the bucket is emptied on the ground and a conical heap of sand is formed, the height of the heap being 12 cm. the radius of the heap at the base is :
Options: ['a. 63 cm', 'b. 53 cm', 'c. 56 cm', 'd. 66 cm', 'e. none of these']
Output (English): a