Finish the following sentence with the best choice: To make aioli.

Choices:
- To make aioli Whisk the shell of an egg using a stand mixer with the whisk attachment, and gradually drizzle in half a cup of vegetable oil, drop by drop at first, until aioli is thickened and smooth. Whisk in your flavourings of choices, and season with salt to taste.
- To make aioli Whisk the yolk of an egg using a stand mixer with the whisk attachment, and gradually drizzle in half a cup of vegetable oil, drop by drop at first, until aioli is thickened and smooth. Whisk in your flavourings of choices, and season with salt to taste.

Answer:
To make aioli Whisk the yolk of an egg using a stand mixer with the whisk attachment, and gradually drizzle in half a cup of vegetable oil, drop by drop at first, until aioli is thickened and smooth. Whisk in your flavourings of choices, and season with salt to taste.