It's important to know that diffraction gratings can be identified by the number of lines they have per centimeter. Often, more lines per centimeter is more useful because the images separation is greater when this happens. That is, the distance between lines increases.
<h2>Therefore, the answer is 2.</h2>
Sweat is slightly acidic which helps to protect the body.
<em>(Please mark this answer as Brainliest and leave a Thanks if I helped you!)</em>