A function`f: Rvec[1,oo)` satisfies the equation `f(x y)=f(x)f(y)-f(x)-f(y)+2.` If differentiable on `R-{0}a n df(2)=5,f^(prime)(x)=(f(x)-1)/xdotlambdat h e nlambda=` `2^(prime)f(1)` b. `3f^(prime)(1)` c. `1/2f^(prime)(1)` d. `f^(prime)(1)`