A person is to count `4500` currency notes. Let `a_n`, denote the number of notes he counts in the `nth` minute if `a_1=a_2=a_3=..........=a_10=150` and `a_10,a_11,.........`are in an `AP` with common difference `-2`, then the time taken by him to count all notes is :- (1) 24 minutes 10 11 (2) 34 minutes (3) 125 minutes (4) 135 minutes