Rohan keeps a total of 90 guppies in 4 fish tanks.
- There is 1 more guppy in the 2nd tank than in the 1st tank.
- There are 2 more guppies in the 3rd tank than in the 2nd tank.
- There are 3 more guppies in the 4th tank than in the 3rd tank.
Question: How many guppies are in the 4th tank?
Answer Choices
A. 20
B. 21
C. 23
D. 24
E. 26