Finish the sentence with the word resistance. To avoid getting sick

Stay away from people who are sick with resistance

There are many ways you can use this word, but ultimately, you need to develop a resistance to the germs in order avoid getting sick. The answer you have been given does not use the word correctly (although A for the effort). I would write it as, "To avoid getting sick, one must develop a resistance to the germs or virus that is causing the illness."