Researchers find an interesting geological formation on the ocean floor. how can they tell whether plates are colliding or moving apart due to spreading seafloor in this region?

In order for the researches to determine weather the seafloor is spreading or colliding they should look for the typical geological formations in both scenarios.

If there's a trench on the seafloor, than that will mean that the plates are moving towards one another. Because one of them is subducting bellow the other one, on the place of subduction there will be a trench.

If there's a mid-ocean ridge on the seafloor, than that will mean that the plates are moving away from one another. Because the plates are living space between them, and the crust becomes less thick, the high pressure, temperature, and magma from the mantle will penetrate through, with constant magma flows that will cool off very quickly, and create an underwater mountain range.