Oh my God, this is so confusing
The high arched palate and the long limbs are pointing to Marfan syndrome.
But what has that got to do with the neck mass?
If it is a thyroglossal cyst then it must share the same origin with the thyroid and therefore endoderm and therefore choice F is the correct one.
But what if the mass is a branchial cyst because it's mentioned a little to the right!