You are formatting a single hard disk for a Linux install. What is the maximum number of primary partitions you can create?

Zero is not the maximum; at least one primary partition is required to hold a bootable operating system.

One primary partition is valid but is far below the maximum the MBR table supports.

Two primary partitions is valid but is not the maximum.

Three primary partitions is valid but is not the maximum.

The MBR partition table allocates exactly 4 fixed 16-byte entries in the first sector of the disk, limiting the number of primary partitions to 4. To use more than 4 partitions on an MBR disk, one of the 4 primary slots must be designated as an extended partition, which can then contain additional logical partitions.

Five primary partitions is impossible under MBR because the partition table only has 4 slots; GPT must be used to exceed 4 primary-style partitions.