Final answer:
Option 3, 'he went to take a rest,' best maintains the original meaning and tone of the underlined excerpt by reflecting the character's deep exhaustion and need for rest.
Step-by-step explanation:
The adaptation that best maintains the original meaning and tone of the underlined part of the excerpt 'he is probably pretty tired' is option 3) he went to take a rest. This option closely mirrors the context of fatigue and the action of seeking rest that is conveyed in various parts of the provided excerpts. Throughout the passages, there's a repeated emphasis on the character's need for rest and not just sleep, reflecting a deeper level of exhaustion that aligns with taking a rest rather than just leaving or sleeping.