Mark has a certain number of songs on his MP3 player.
Each week, he plans to add 4 more songs. After 5 weeks, he
had 40 songs on his MP3 player. Which statement is true?

A. Mark adds 5 songs on his MP3 player per week.

B. Mark adds 10 songs on his MP3 player per week.

C. The initial number of songs on Mark's MP3 player is 10.

D. The initial number of songs on Mark's MP3 player is 20.