Help with finishing plumbing for roughed-in basement bathroom

[westerbamos]

Hey everyone,

I know almost nothing about plumbing so apologize for the very simple questions. I'm in the process of finishing my basement, and trying to figure out how to go from what my home builder roughed in to a finished bathroom. The toilet is roughed in, and there's an X on the ground (underneath the wood pile in the attached picture) that marks where I can hook the shower drain into the drain line-- those are straightforward. Where I'm struggling is where to route the pipes for the bathroom sink. Would I be routing the drain line into the large pipe on the left side of the attached picture? Should I instead be opening up the concrete to find the drain line underneath and tapping in there? Appreciate any help you can provide, and again, apologies for the rudimentary questions.

Thanks