Assume that you have two alternative jobs.

Alternative $1$: With a salary of SAR $7,000$ per month in your city of Riyadh.

Alternative $2$: You have a job offer in the city of Madinah that pays SAR $8,300$ per month and the commuting cost to the eity is SAR $700$ per month.

The differential revenue in the two alternatives would be:

$$ a$.$ SAR $600$

$$ b$.$ SAR $1300$

O c$.$ SAR $1\mathrm{.}000$

$$ d$.$ SAR $700$