Answer:
B
Step-by-step explanation:
Paul says 'I'm very thirsty'.
Therefore he should say 'Could I drink water', or something like that.
A- Can I close the door? - Wrong
B- Can I go drink water? - Correct
C- Can I open the windows? - Wrong
D- Can I borrow a pen? - Wrong
Conclusion: B is Correct.
Hope this helps!