The answer is A. All of the angles in a triangle add up to 180 degrees. For an angle to be obtuse, it has to be over 90 degrees. Therefore , when added together angle Z and Y must equal less than 90 degrees (since 180-90=90). Then you know that angle Z and Y are congruent (meaning their measures are the same), so each angle must be less than 45 degrees (since if one was say, 50, then the other has to be the same, making the two add up to 100 and the other angle being 80, so it wouldn’t be obtuse anymore). Hope that helps :)
