The most accurate partial explanation for "gaps" in the fossil record is:
Fossilization is a rare phenomenon because an organism’s remains must be covered by sediment and stay undisturbed for thousands of years.
This statement addresses the rarity of fossilization and explains why certain organisms may not be represented in the fossil record, leading to gaps. Fossilization requires specific conditions to occur, and many organisms do not survive long enough to be buried and preserved.