If 12! = 2^a3^b5^c7^d11^e then,

1. a=5c
2. a=1-d
3. b=5e
4. none

Just open the expression as 12*11*10*9*8*7*6*5*4*3*2*1 and now write as power of 2,3,5,7, and 11 then you get a= 10, b = 5, c = 2, d=e= 1. So correct option is a=5c and b =5e