Which of the following standard libraries can be used to convert time zones?

The correct answer is based on the functionality offered by the datetime library in Python. This library provides a variety of tools for manipulating dates and times, including support for time zones. Specifically, the datetime module includes the timezone class which allows for the representation and conversion of datetime objects to various time zones.

In addition to this, the library can handle operations to convert times from one zone to another, making it very useful for applications that need to manage multiple time zones effectively. The datetime library accommodates both naive and aware datetime objects, where aware objects are those that carry information about the time zone.

The random, math, and time libraries, while valuable in their own contexts, do not provide the mechanisms necessary for time zone manipulation. The random library deals with random number generation, the math library provides mathematical functions, and the time library focuses more on low-level time operations and does not directly support time zone conversions.