Maxima and Minina

For the curve y = x^2, shortest distance from variable point (0,c) to the curve is described by 'd' = f(c) where c belongs to R and d belongs to [0,∞)

then f(c)
(a) one-one, onto
(b) many-one, onto
(c) many-one, into
(d) one-one, into

2. Number of points for which f(c) is not differentiable is
(a) 0
(b) 1
(c) 2
(d) 3

3. f(c)
(a) increases for all its domain
(b) decreases for all r
(C) decreases for all c<0
d) none of these