A shopkeeper places before you 41 different toys out of which 20 toys are to be purchased. Suppose `m=` number of ways which 20 toys can be purchased without any restriction and `n=` number of way in which a particular toy is to be always included in each selection of 20 toys, then `(m-n)` can be expressed as `(2^(10))/(20 !)(1. 3. 5 39)` `(2^(20)(1. 3. 5 19))/(10 !)` `prod_(r=0)^(19)((4r+2)/((20-r)))` `((21)/1)((22)/2)((23)/3)((40)/(20))`

Options

A. `(2^(10))/(20!)(1.3.5"….."39)`
B. `(2^(20)(1.3.5"….."19))/(10!)`
C. `underset(r=0)overset(19)(II)((4r+2)/((20-r)))`
D. `(21/1)(22/2)(23/3)"…."(40/20)`

Answer

A