Select the correct answer.
Mary and Nikki are collecting signatures for a petition. Function m models the total number of signatures on Mary’s petition x days after they started collecting signatures. Function n models the total number of signatures on Nikki’s petition at the same time.
m(x) = 252 + 21x
n(x) = 211 + 16x

Which function correctly represents the number of signatures Mary and Nikki have gathered altogether, x days after they started collecting signatures?
A. (m + n)(x) = 41 + 37x
B. (m + n)(x) = 463 + 5x
C. (m + n)(x) = 463 + 37x
D. (m + n)(x) = 41 + 5x