Answer: Sleepiest
Step-by-step explanation:
A superlative adjective is one that describes a noun with the highest or lowest degree of quality.
When comparing three or more people, places or things, a superlative adjective is used to describe them.
Examples include;
• Tallest
• Smartest
• Biggest, e.t.c
Sleepiest is the correct answer because it is the superlative form of “sleep” that is used to show the degree to which one is sleepy.