It tried Synthesis in the past. But failed because it can't be 'forced" Although with Shepard here now, I guess it can be forced.
Yes, but before creating the Reapers it did collect data and showed it was willing to approach and consider different ideas until it found a solution. It even says in the ending "but our efforts always ended in conflict, so a new solution was required". That sounds to me as if it has tried out several solutions and none of them worked. So it thinks the Reapers are the best solution. I dislike its solution, too, but the Catalyst's assumption it's the best solution for itself is valid. Also, it acknowledges that its solution won't work anymore in the end, so it is open to a new solution.
And the part "It gives you "choices " on its terms" is not really right, Control and Destroy could become choices because of the Crucible. And since the Catalyst was changed by the Crucible, it presents the choices, but it's not coming from the Catalyst directly.
The only choice it offers in its own terms is probably Synthesis, because the energy coming from the Crucible + Shepard can finally achieve it.
Fact is, if the Crucible would not have docked, none of the choices would have been possible if Shepard still reached the Catalyst.
Yep, and a Shepard who considers Synthesis as the best solution will go for it, the rest will settle for something else.