Enclosure - recinto
There are more elefantes than dogs - <span>Hay más elefantes que los perros</span>
B. Fueron
Fui is speaking in terms to yourself
Fueron is the best choice because you are talking about what your grandparents did or were they went, in this case you can almost assume the grandparents were doctors there for B. Is the appropriate response.
Yo pensé que es cierto pero no se si ese es la respuesta
3, I think it’s the third one
It would tienes because it goes with tú. I'm not sure how to really explain it but that's the ser you would use with tú. I hope this helps!