A team of swimmers was training.
Claire was the first swimmer for the team and she swam 100 metres.
Every other swimmer in the team swam 50 metres further than the previous swimmer.
Jane was the last swimmer for the team and she swam 800 metres.
The total number of swimmers in this team was
A. `9`
B. `13`
C. `14`
D. `15`
E. `18`