The commission took two years to go through the massive collection of files and documents before preparing its report.

Answer: Option D

Massive : large and heavy or solid.
Ugly : unpleasant or repulsive, especially in appearance.
Short : measuring a small distance from end to end.
Light : the natural agent that stimulates sight and makes things visible.
Meagre : (of something provided or available) lacking in quantity or quality.
Antonym of Massive is Meagre