The cropping is not accurate to the question asked at the debate, but every candidate there signed a pledge to back whoever wins the GOP primary, and right now that includes Trump as an option.

So for Hutchinson and Christie, the only way this image is not an accurate representation of their stances (if not how they answered the question on stage) is if we assume that they were lying when signing the "loyalty pledge" document that was a requirement for even being on the stage at all.

Christie in particular opposed Trump in the 2016 election....all the way until Trump got the nomination, at which point Christie became an ardent Trump supporter. I think it's reasonable to assume this is a repeat of that track record on his part.