If f(x) is a cubic polynomial which has local maximum at x=−1. If f(2)=18, f(1)=−1 and f′(x) has local minimum at x=0, then
a. the distance between (−1,2) and (a,f(a)) , where x=a is the point of local minima, is 25
b. f(x) is increasing for x∈[1,25]
c. f(x) has local minima at x=1
d. the value of f(0)=5