I don't understand why sentence 1 is accepted. I thought "and" is translated as і, та, а. I don't recall й being translated as "and." Did I miss something or is this a mistake?
Й/і is the same conjunction. More here: https://www.duolingo.com/comment/9012790
Грати в теніс? Not 'грати у теніс?
I saw "грати у телніс" as the only variation, but both are acceptable I think.