Final answer:
The scarcity of intermediary forms in the fossil record can be explained by preservation bias.
Step-by-step explanation:
The scarcity of intermediary forms in the fossil record can be explained by c. Preservation bias. Preservation bias refers to the fact that the conditions required for fossilization are rare, and only a small fraction of all organisms that have ever lived are preserved as fossils. Therefore, the fossil record is incomplete and biased towards certain types of organisms or environments that are more likely to fossilize. This bias can result in a lack of intermediate forms in the fossil record.