Correct Answer: add

Solution : The correct choice is the fourth option.

Explanation:

• Aide refers to a person who helps or assists, which is not suitable in the context.
• Ad is a short form of advertisement and doesn't fit the context.
• Aid means assistance or help and is not appropriate in this context.
• Add is the correct homonym, meaning to include something, and it fits the context of adding sugar to the juice.

So, the correct sentence would be: "Please add more sugar to the juice so that it becomes sweeter."