My approach: in 2s complement, positive number is taken as its magnitude only excluding sign bit, while for negative number do the 1's complement of magnitude bits and add 1.
here it asked about positive number so magnitude value as it is will be highest number so. all 7 bits should be 1. which can be represented as 11111111 = 127.
even i also marked 127 so need some expert advice. @bikram sir. @habib