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

Problem: two diagonals of a rhombus are 72 cm and 30 cm respectively . what is its perimeter ?
Options: ['a ) 136 cm', 'b ) 156 cm', 'c ) 144 cm', 'd ) 121 cm', 'e ) 126 cm']
b

Problem: the speed at which a man can row a boat in still water is 15 km / hr . if he rows downstream , where the speed of current is 3 km / hr , how many seconds will he take to cover 90 meters ?
Options: a ) 12 , b ) 16 , c ) 17 , d ) 18 , e ) 20
d

Problem: in a garment industry , 12 men working 8 hours per day complete a piece of work in 10 days . to complete the same work in 8 days , working 5 hours a day , the number of men required is :
Options: a ) 24 , b ) 5 , c ) 6 , d ) 8 , e ) 9
a