The horizontal distance x and the vertical height y of a projectile at a time t are given by `x=at` and `y=bt^2 +ct` where a, b and c are constants The magnitude of the velocity of the projectile 1 second after it is fired is

Options

A. `[ (a^2 +(2b + c)^2]^(1/2)`
B. `[ (2a^2 +(b + c)^2]^(1/2)`
C. `[ (2a^2 +(2b + c)^2]^(1/2)`
D. `[ (a^2 +(b + 2c)^2]^(1/2)`