This is basically a direct proportion equation,
y = kx
in this case, it’s :
225 = k2
to get k, we have to divide 225 by 2 hence:
112.5 = k
k = 112.5
Since the answer match none of the multiple choice you provided.
You must’ve written the question wrongly, if you were writing to the power of 2, it means u should have written k^2 = 225.
In this case, it’s not a direct proportion question and it’s a case of simple algebraic equation.
k^2 = 225
Then
k = +/- 15.
Hence the answer is both C and D