Final answer:
Time Machine can back up to any external hard drive that is formatted as HFS+ (Mac OS Extended), irrespective of whether it’s an HDD or an SSD.
Step-by-step explanation:
The Time Machine backup software is a feature on Mac computers that can back up data to various kinds of external hard drives. The correct answer to your question is that Time Machine can back up to any drive formatted as HFS+ (option B). This file system is also known as Mac OS Extended. Time Machine requires a drive to be formatted with HFS+ because it needs to manage and organize backups with a complex linking system that other file systems do not support.
Other formats like FAT32 or exFAT are not supported because they lack certain features needed by Time Machine, like the ability to set file permissions and create hard link backups, which are essential for Time Machine's incremental backup feature. Additionally, although Time Machine works with both HDDs and SSDs, the format of the drive is the essential criterion, not the drive type.