how to combine text with a semicolon if there's text in 2 columns

Hi,

Is there ONE forum for that can take care of the following situations:

Text in column A
Text in column B
Column C = A; B

Text in column A
NO text in column B
Column C = A

NO text in column A
Text in column B
Column C = B

Sample sheet of how I'd like column C to be attached.

Thanks in advance.