The is the innermost layer of the sun's atmosphere.
a. heliosphere
b. solar prominence
c. photosphere
d. chromosphere

The innermost layer or the lower most layer of the Sun's atmosphere is called the photosphere. It is the visible surface of the sun that we are most familiar with. The sun is a ball of gas; however, the solid shape we see is actually just a layer which is about 100 km thick. The correct answer to this question is letter "C. Photosphere". 

Answer glacier terminus;

Answer sinking and cooled;