Correct Answer: Peaceful

Solution : The most appropriate synonym for the word "tranquil" is the fourth option.

"Tranquil" means calm, serene, and free from disturbance. "Peaceful" conveys a similar meaning, as it also suggests a lack of disturbance, noise, or agitation.

The meanings of the other options are as follows:

• "Anxious" means feeling uneasy or worried, which is the opposite of "tranquil".
• "Dilemma" refers to a difficult choice or situation that is unrelated to tranquillity.
• "Fierce" means intense or violent, which is the opposite of "tranquil".