Why are there more younger stars than older stars in the galaxy
4-5 sentences
answer

True, as the stars get old its gravity and density consume itself , the more massive star more short is its lifespan

Explanation:

As the galaxy is a collection of millions and billions of stars, which are held by gas and dust together. There are thus four types of galaxies like a spiral, barred, elliptical and Irregular. These galaxies hold stars that are born from 1bn to 10bn years ago and some stars may even be close to 13.8 billion years old. As the scientist measures the luminosity and spectral motion through space telescopes.  This technique is called as the geochronology, the speed of rotating stars depends on the age and color composition.b The stars of younger origin are present in disk-shaped galaxies. The older are metal-poor stars found in the galaxies nuclear bulge, and global clusters. Stars need to sustain themselves and thus their core becomes much more important than that outside galaxy as the dominance of heavy metals and elements in the stars is the founding matter that leads to there origin.

D. i believe that doesn't even exist.

I'm going to say it's 5-6 million