Foreground process & Background process

Someone please explain the following answer on how it is calculated and the difference between foreground & background process. ( I came across the following Q&A in a website)

Which of the following sets of jobs can be run simultaneously using a pool of 4 machines connected using the same machine template having 2 runtimes?

3 jobs created using a foreground process and 5 jobs created using a background process

5 jobs created using a background process

Among these 2 options, first one seems the right choice.
We can run N number of background processes on a single machine whereas each foreground process requires a separate machine.

Thus 3 foreground process on 3 machines and 5 / N jobs of background process on 1 machine

Hello @Jeyalakshmi_KS

Can check the below.