Q: In this task, you need to answer the given multiple-choice question on geometry. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.
Problem: if ( 20 ) is subtracted from the square of a number , the answer so obtained is 4321 . what is the number ?
Options: ['a ) 68', 'b ) 69', 'c ) 70', 'd ) 71', 'e ) 72']
A:
b