Answer:
A. Height is input, Weight is output
Explanation:
We are given the statement,
"Weight is a function of height".
As we know,
In a function of the form
, the input variable is 'x' and the output variable is 'y'.
If we write the given statement in the form
, we get,

This means that the input variable is 'Height' and the output variable is 'Weight'.
Hence, option A is correct.