The A option is correct.
A ratio is an ordered pair of numbers a and b, written as a/b where b does not equal 0. A proportion is an equation in which two ratios are set equal to each other.
Given
The interest rate applied to the present value has on the monthly payment P in the formula
[tex]\rm P = PV(\dfrac{i}{1-i})^{-n}[/tex]
The effect an increase in i.
[tex]\rm P = PV(\dfrac{i}{1-i})^{-n}\\[/tex]
on simplifying the equation, we get
[tex]\rm P = PV(\dfrac{i}{1-i})^{-n}\\\\P = PV\dfrac{1}{(\frac{i}{1-i})^n}\\\\\\P = PV(\dfrac{1-i}{i})^{n}\\\\P = PV(\dfrac{1}{i} - 1)^{n}[/tex]
Let n be the constant, then the equation will be
[tex]\rm P = PV(\dfrac{1}{i} - 1)^{n}\\\\\dfrac{1}{V} \propto \dfrac{1}{i}\\\\V \propto i[/tex]
It is clear that V is proportional to i.
An increase in i, the interest rate, will not change P, the monthly payment.
Thus, the A option is correct.
More about the ratio and the proportion link is given below.
https://brainly.com/question/165414
