Conversation so far:
what type of fibres pass through the corpus callosum
The corpus callosum is a wide, thick nerve tract, consisting of a flat bundle of commissural fibers.
what tracts do the commissural fibers make up?
Commissural fibers make up the corpus callosum, the anterior commissure, and the posterior commissure of the brain.

Question: which tract is the largest?
Self-contained rewrite: which tract in the brain is the largest?