Ted is talking about his brother choose the correct word (a,b

Ted is talking about his brother choose the correct word (a,b or c ) to fill in the gaps in the sentences there is an example (0) at the beginning. My brother Chris is my example to (0) follow. In his class he is very popular and I can say that he is the (1)____ of the class.He has invented a (2)____ that helps mum in her garden work.And I think he'll be an (3)___. But he says he wants to study (4)_____.If he studies it on Earth he'll be a (5)____, and if he studies it on board a spaceship he'll be an (6)_____.But I want him to invent a new medicine or a new machine that could help to (7)___people with serious diseases.It's wonderful to help people in _____.
1 explorer scientist leader
2 medicine collection machine
3 astronaut inventor hero
4 machines history space
5 scientist leader doctor
6 astronaut engineer actor
7 develop follow treat
8 disease trouble action