The exosphere is the layer of the atmosphere "Where gas molecules can be exchanged between Earth's atmosphere and outer space." Thus, the answer would be C.
Answer:

Explanation:
By energy conservation and work energy theorem we can say that after bullet hits the block, it will move on the rough floor and comes to rest
so here work done by frictional force = change in kinetic energy
so we know that





now by momentum conservation we have



From the point of view of the northern hemisphere:
The sun starts out the year at the Spring equinox, March 21,
Right Ascension 0, Declination 0.
3 months later, Summer solstice, June 21
RA = 6 hours, Dec. = +23.5°
3 months later, Fall equinox, September 21,
RA = 12 hours, Dec. = 0
3 months later, Winter solstice, December 21,
RA = 18 hours, Dec. = -23.5°
An upright base / 6ft long