The correct option is
D 100 billion light years.
The universe (Latin: universus) is all of space and time and their contents, including planets, stars, galaxies, and all other forms of matter and energy. At the largest scale, galaxies are distributed uniformly and the same in all directions, meaning that the universe has neither an edge nor a center.According to current thinking it is about 93 billion light years in diameter.
So the correct answer is option D.