What happens to the surface temperature and radius of a star like the sun as it goes from the main sequence to the red giant branch?

Temperature decreases as the radius increases.

Explanation:

According to my research on the evolution of a star, It is said that a red-giant branch is the part before helium ignition occurs during the course of a stars evolution. Based on this information and the information provided within the question, I can say that during the change between the main sequence to the red giant branch, Temperature decreases as the radius increases.

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