A rare bacterial culture is being grown in a lab. As time passes, the cells multiply in a specific pattern.


After 1 day, there is only 1 cell.

After 2 days, there are 5 cells.

After 3 days, there are 10 cells.

After 4 days, there are 16 cells.


How many cells will there be after seven days?


A. 40

B. 50

C. 60

D. 70