The previous one didnt say it so.
Thanks
But, others told me'
'Nado,
Are you sure you've quoted the question accurately?
If so, it's wrongly worded and incapable of being answered correctly.
I would agree that the question is badly worded! If they were simply trying to get you to find the correct noun to agree with "problem" then that doesn't really matter, but the correct form should have been:
We should (or must) find
a/the solution to the problems of internet shopping.
In my opinion "to avoid" should not have been used. A way of saying it, including "to avoid" would be:
"We need to find a way to avoid internet shopping problems."
It's unfortunate that quite regularly the questions in English exercises, tests or exams are not written by native speakers, so we see errors even in the questions.