Interview question

[Sergei Troizky]

At a recent interview, i was asked why data is transmitted using hexadecimal values.
...

The question is initially incorrect.
Data is NOT transmitted using hexadecimal values.
Any data is transmitted, stored and processed using binary values, that is bits.
It is up to user (system itself or human observer) to combine them into words and interpret the format.
For practical purposes, Hexadecimal is nothing but a compact notation of binary code.