Which of the following can be used to determine the temperature of a star?
a. light from sunspots
b. line spectra
c. blackbody spectrum
d. the star's magnetic field

A. Light from sunspots

Explanation:

Sunspots are darker, cooler areas on the surface of the sun in a region called the photosphere.

The photosphere has a temperature of 5,800 degrees Kelvin. Sunspots have temperatures of about 3,800 degrees K. They look dark only in comparison with the brighter and hotter regions of the photosphere around them.

the bal will not change its velocity.

blue light is scattered in different directions by the tiny molecules of air. blue is scattered more than other colours because it has a shorter distance to travel which results in smaller waves. this is why we see a blue sky most of the time.