Question

In which sentence does the subject correctly agree with the verb? The saguaro cactus, native to southern Arizona and northern Mexico, have been known to live as long as two hundred years. The branches of a saguaro, also known as arms, are covered with white flowers in the spring and red fruit in the summer. When a saguaro dies, either the woody ribs or the hollow “saguaro boots” is used for construction and water storage. Temperature and elevation, both important environmental factors, affects the growth and health of a saguaro.

Answer 1

I would say Temperature and elevation, both important environmental factors, affects the growth and health of a saguaro.

not sure

Answer 2

The one that begins with "the branches..." I'm sure ^^

Answer 3

The saguaro cactus, native to southern Arizona and northern Mexico, have been known to live as long as two hundred years. ~Incorrect, because here the singular noun 'cactus' is being used with the plural verb 'have'.

The branches of a saguaro, also known as arms, are covered with white flowers in the spring and red fruit in the summer. ~Correct, because the plural noun 'branches' is being used with the plural verb 'are'.

When a saguaro dies, either the woody ribs or the hollow “saguaro boots” is used for construction and water storage. ~Incorrect, because the combined nouns 'ribs' and 'boots' are considered plural, but are being matched with the singular verb 'is'.

Temperature and elevation, both important environmental factors, affects the growth and health of a saguaro. ~Incorrect, because 'temperature and elevation' are plural and are used with the singular verb 'affects'.

Hope that helped *^-^
Good Luck~