Multi-choice problem: Choose from the options at the end, and answer how do you do this: To create lemon zest.

Choices:
-For the lemon zest, grate only the inner yellow skin. Avoid using the outer white skin as it will have a bitter taste. The lemon zest will brighten up all the flavors in the muffins.;
-For the lemon zest, grate only the outer yellow skin. Avoid using the inner white skin as it will have a bitter taste. The lemon zest will brighten up all the flavors in the muffins.;
For the lemon zest, grate only the outer yellow skin. Avoid using the inner white skin as it will have a bitter taste. The lemon zest will brighten up all the flavors in the muffins.