What condition should be met for the stellar parallax method to be useful?

a. the star should be situated within the milky way

b. the star should be brighter than the sun

c. the star should be close enough to the sun to show a measurable parallax

d. the star should be visible with the naked eye

The answer is: C. the star must be close enough to the Sun to show measurable parallax.

Explanation:

In the field of astronomy, parallax is called stellar parallax in distant stars.

The stars for which parallax measurements have been made are those that are relatively close to the sun on the galactic scale.

The answer is: C. the star must be close enough to the Sun to show measurable parallax.