Someone

which area formula or formulas show(s) a joint variation?
i a=s^2
ii a=pir^2
iii a=l*w

select one:
a. iii only
b. ii and iii
c. ii only
d. i, ii, and iii

Joint variation equation is a situation when the final value varies by two or more variables

Equation 1

A = s²

Here we have only one variable, 's', and the value of Area will only vary when s varies.

Equation 2

A = πr²

Here the only variable is 'r', which is the radius of a circle. The value of Area, A, varies as radius varies. π is a constant.

Equation 3

A = l×w

Here we have to variables, the 'l' and the 'w'. 
We can say that the value of Area, A, will vary jointly as l and w vary

The correct answer is option a)

We need more info then that