Explain why the distance between parallels is constant but the distance between meridians decreases as the meridians approach the poles.

The distance of parallel is always constant as it is the perpendicular distance from a point on one line to the other line so it does not matter which point is chosen to measure the distance. While for meridians  the distance between poles decreases as you near the poles as the circumference of the earth is lower as you near the poles.

Brazzaville and kinshasha, luanda,librevilleand and monrovia.