What are the two ways a company may address the issue of double taxation for an expatriate?

Multiple select question.

Pay the expatriate's income tax in the home country

Make up the difference when a higher rate in the home country reduces the expatriate's take$-$home pay

Make up the difference when a higher rate in the host country reduces the expatriate's take$-$home pay

Pay the expatriate's income tax in the host country$\backslash$