I believe the answer to the first question of the F324 paper may be the first acid (stearic?)
This was the only option which was clearly saturated. And as the textbook states on page 34 "saturated fats have been known for many years to increase the risk of heart disease by raising blood cholesterol levels."
However technically if either of the other acids were trans fats then they would also be a risk factor so perhaps (optimistically) with the correct reasoning any answer could be feasible? Countering that I seem to remember the wording of the question being chose the option most likely.
Given the style of this question, the PLA stitches and others I would be surprised if the grade boundaries are dramatically high as these have caught many out, me included.