Answer:
By not eating things that are not lactose free
Explanation:
If this is not helPaul plz let me know
If you really can't move your arm because of the sting, and there is pus, the best thing you can do to yourself is go to the Emergency doctor. You can take an ibuprofen if the pain is too hard.
Not sure how this has to do with Health but my answer would be to not buy things online at all. Nowadays it's EXTREMELY easy to get robbed of your money, by people that live across the world. Your bank account can easily be accessed through a phone, computer, gaming system, credit/debit card, check book, etc. I covered things both online and off. Stay safe!
I believe the answer is (a) variability