Final answer:
The Mopar product designed for retrofitting classic muscle cars with modern HEMI engines is the Crate HEMI. It includes the engine and necessary components for installation.
Step-by-step explanation:
The name of the Mopar product that allows owners to easily retrofit their classic muscle cars with current HEMI power is C) Crate HEMI. Mopar provides a range of crate engines, which are complete engines that can be installed into a vehicle. The Crate HEMI engine kits are designed to make it easier for enthusiasts to place modern HEMI engines into older muscle cars, thereby upgrading their performance with today's technology. This includes providing the engine itself, as well as necessary wiring harnesses, control modules, and other components vital for a seamless integration into classic vehicles.