Answer:
Don't smoke.
Eat a diet high in fruits and vegetables.
Exercise regularly.
Maintain a healthy weight.
If you drink alcohol, drink only in moderation.
Get adequate sleep.
Take steps to avoid infection, such as washing your hands frequently and cooking meats thoroughly.
Explanation:
(A.) is your answer to the question
B. A possessive noun should have its instead of it's (which is a contraction for it is).
For A. Diana is a singular noun and the apostrophe should come after the r instead of after the s.
For C. The duck would've dunked ITS instead of IT'S beak since it is possessive.
For D. You do not need to put an apostrophe since theirs is already a possessive noun.