Even drinking was difficult after the surgery, he was having trouble doing what?
Options:
- coloring
- glass
- swallowing
- use glass
- mouth
Let's think carefully first. Step-by-step reasoning process:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Drink required swallowing. Drink was difficult after surgery. Swallowing troubles more after surgery. So the final answer is swallowing.