Answer:both occur at convergent
Explanation:
I might be wrong but i think is C
A) The stars core shrinks
The star will contract under the weight of gravity.
When it contracts it will heat up and expand to a red giant.
When the star runs out completly of helium it would emit gasses and form a star nebula.
It would then become a white dwarf then into a black dwarf.
They can help people by making maps for countries so then they know where things are