Which two font sets are most commonly used and available?

The most commonly used and available font sets are often recognized for their readability and versatility across various platforms and devices. Among the choices given, the first selection—Times New Roman, Times, and Serif—validates its widespread availability, especially in documents and web content due to its long-standing presence in typesetting and digital formats. Times New Roman is a classic serif font that is standard in many word processing applications and is favored for formal documents.

Additionally, these fonts are part of a broader category of serif typefaces, which are frequently utilized in printed materials and formal correspondence due to their traditional appearance. The presence of "Serif" as a generic typeface indicates the use of any serif font, offering flexibility in design while still adhering to familiar typography that most users recognize. This option underscores the importance of conventional and universally accessible typefaces in both web and print design.

In contrast, while the other selections include popular fonts, they may not collectively embody the notion of the most commonly used sets as effectively as the first option does.