I need help trying to understand this; I why is the answer the right answer.

Which of the following is the correct formula for the constant-growth DDM (Gordon Growth Model)?

Group of answer choices

A. Po = Div1 (I/Yr - g)

B. Po = Div0 x (1+g) / (I/Yr - g)

C. Both A & B

D. Neither A or B

Also, i would like to confirm another questions

#2 A firm will pay dividends of $1.50, $2.00, and $2.50 over the next three years. After that, the stock will be sold at the end of year 3 for $50. If the required return is 10%, what is the value of the stock?

My answer was 42.47