Turning off synchronization with iCloud on Mac

I recently bought some iCloud space because I need a backup and most importantly because I need more space on my Mac.

I just synchronized all my photos (they are now on the Mac and the iCloud) and I have some questions for security:

If I turn off the synchronization on Photos on my Mac and delete all the pictures in the computer, I suppose that the will stay in the cloud. But if I turn on the synchronization again, what happen?

a. They will also be erased in the cloud ?

b. They will be loaded in my computer again ?

c. Something else

I'm asking because I don't really need them on my computer. And finally, does it work exactly the same if I do that with my phone?