Let $P_{n}$ Be the Number of People Visiting a Zoo on the on the N^th

Multiple Choice

Let $P_{n}$ be the number of people visiting a zoo on the n^th day after it opens.What does $\sum_{n=1}^{25} P_{n}$ represent?

A) The average number of people visiting the zoo over the first 25 days it was open.
B) The number of days it takes for 25 people to visit the zoo.
C) The number of people visiting the zoo on the 25^th day it is open.
D) The total number of people who visited the zoo in the first 25 days after it opened.