Question

________ are there in the room? They are three chairs.

Escolha uma:
a. How much chair.
b. How many chairs.
c. How much chairs.
d. How many chair.

Answer 1

b. How many chairs

How many chairs are there in the room?
There are three chairs.

Answer 2

b. How many chairs

"chairs" is countable and has a plural, so you can just use many
many means "Muitas/muitos"
much means "Muita/muito"