Image by Kmf164 On the world map above, which lines are highlighted and are moving from west to east

Ithink the answer is either a , c or d

1. why do astronomers think that there may be other advanced civilizations?
because  it was discovered that there are other planets like earth out there, able to  accommodate life forms.
2. what technologies are astronomers using to look for life on other planets? why?  
they  have used radio telescopes, but now they use laser telescopes   to track laser communications.

The correct answer to this question is choice " m∠mnp = (x – y)"

far arc = x
near arc = y

angle mnp = (far arc - near arc) / 2
angle mnp = (x - y) / 2

from the given choices, it is assumed that there is a denominator of 2 that divides the whole expression.