Imagine that you are living away from home. your sister at home is rather carefree about food work and rest ans is spoiling her health. write her a persuasive letter telling her how she can improve her health.

Focus on your health.

Explanation:

Dear sister, as you know that i am living away from home and you have to take care of yourself along with home chores. I know you are not taking food as well as rest which is very important for your health.

I am going to tell you that how you can improve your health even in my absence when i am not there to take care of you.

Please follow these steps which will boost your immune system.

Always remember leading a healthier life doesn't have to mean making big changes.

the correct answer would be:  

a. adverb phrase

a. is the correct answer