Correct Answer: expecting

Solution : The third option is correct.

• The sentence is talking about the speaker watching someone with excitement.
• The word expecting means anticipating or waiting for something to happen.
• The speaker is expecting the person they are watching to do something at any time, which is why they are excited.

Therefore, the correct answer is expecting.

Additional Information

• Lacking means not having something.
• Excepting means excluding or leaving out.
• Accepting means agreeing to or receiving something.