A scientist is studying the population growth rates of two different types of bacteria under the same laboratory conditions. The number of bacterial cells of type A is represented by the equation shown, where P represents the number of bacterial cells at the end of x hours.

P = 2^x + 19

The number of bacterial cells of type B is represented by the equation shown, where Q represents the number of bacterial cells at the end of x hours.

Q = 3^x + 18

Which statement is true?

A. At the end of 21 hours, there will be the same number of bacterial cells of type A and type B.
B. At the end of 3 hours, there will be the same number of bacterial cells of type A and type B.
C. At the end of 1 hour, there will be the same number of bacterial cells of type A and type B.
D. At the end of 18 hours, there will be the same number of bacterial cells of type A and type B.