Correct Answer: Finish

Solution : The fourth option is the correct choice.

Embark means to begin or start a journey or undertaking, while finish means to complete or conclude. When someone embarks on a task, he is initiating or commencing it.

The meanings of other options are as follows:

• Board means to get on a ship, aircraft, or other vehicle.
• Launch means to start or set in motion, often used for the beginning of a journey or project.
• Commence means to begin or start.