In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: 50 square stone slabs of equal size were needed to cover a floor area of 72 sq . m . find the length of each stone slab ? 
Options: a ) 120 cm , b ) 767 cm , c ) 88 cm , d ) 666 cm , e ) 776 cm
Example Output: a

Example Input: Problem: while visiting a small town in the united states , i lost my overcoat in a bus . when i reported the matter to the bus company i was asked the number of the bus . though i did not remember the exact number i did remember that the bus number bad a certain peculiarity about it . the number plate showed the bus number as a perfect square and also if the plate was turned upside down . ? the number would still be a perfect square — of course it was not ? i came to know from the bus company they had only 5 100 buses numbered from 1 to 500 . from this i was able to deduce the bus number . can you tell what was the other number . 
Options: a ) 127 , b ) 196 , c ) 116 , d ) 140 , e ) 234
Example Output: b

Example Input: Problem: the curved surface of a right circular cone of height 15 cm and base diameter 16 cm is 
Options: ['a ) 40 ∏ cm ³', 'b ) 60 ∏ cm ³', 'c ) 136 ∏ cm ³', 'd ) 138 ∏ cm ³', 'e ) none']
Example Output:
c