How do you work with other designers?

I received a job at a design agency after working as a solo freelancer for years. I just learned that there are 3 other UI/UX designers on the design team. How do you collaborate with other designers when working on the same project?

Do you:

a) Both work on a design at the same time and talk it out in terms of what edits should be made?

b) Everybody works on their own thing and then both present it to design/product lead and ask the winner moves forward?

I just don't know what to expect.

Thanks!