Answer:
g(t) = 2t+3
Step-by-step explanation:
You want a definition of g(t) so you can write the equation ...
r = g(t) . . . . . . radius is a function of time
We are told the radius at t=0 is 3, so the third choice is the obvious one:
g(t) = 2t +3 . . . . . radius t seconds after the radius began increasing