He is intimidated by his boss.

In the sentence "He is intimidated by his boss," the best replacement for the underlined word "intimidated" is:

"frightened"

Explanation:

• Intimidated means feeling afraid or nervous because of someone's power or authority, which is synonymous with "frightened."
• Promoted means being advanced to a higher position, which is unrelated to intimidation.
• Disliked means not liked, which doesn't convey the sense of fear or nervousness.
• Encouraged means being supported or given confidence, which is the opposite of feeling intimidated.

Thus, the sentence with the best replacement would be:

"He is frightened by his boss."