ㄹ로

걸로 — 'with that one', choosing

In speech 것으로 collapses into 걸로, which is what nearly every line here is. It picks something out — 'I'll find something else', 'the most expensive one', 'what are you going to eat?' — so it is what you say when you order or choose. The other use is 걸로 알다 or 걸로 추측하다, 'I understand it to be' or 'I'm guessing', a way of reporting something without swearing to it. The full form 것으로 is what you write.

Register: spoken contraction