Final answer:
Type X drywall is required between a garage and the floor above as a fire barrier due to its enhanced fire-resistant properties, which include the addition of glass fibers and fire-resistant materials.
Step-by-step explanation:
The type of drywall needed as a fire barrier between a garage and the floor above is c. Type X drywall. Type X drywall is a special kind of drywall that is treated to withstand fire for a longer period of time compared to regular drywall. It is usually required by building codes to be installed in areas where enhanced fire resistance is necessary, such as between a garage and living spaces. This drywall typically contains glass fibers and other fire-resistant materials that help it to resist the spread of flames and provide additional time for occupants to escape and for firefighters to respond.