Which of the following data types would be the best choice for keeping track of player's ages using the least amount of memory?

Using a byte as the data type for keeping track of players' ages is the most efficient choice in terms of memory usage. A byte occupies 1 byte (8 bits) of memory and can store integer values ranging from 0 to 255. Given that the typical age of a player would fall comfortably within this range, the byte is sufficient for this scenario.

In contrast, short, int, and long data types consume more memory. A short requires 2 bytes, an int requires 4 bytes, and a long requires 8 bytes. These options can indeed hold larger values but would be excessive for the purpose of storing player ages, which typically would not exceed 100 for most applications. Thus, choosing a byte allows for efficient memory use while still adequately representing the needed range of player ages.