I suppose it's plausible that someone might interpret the hand and arrow together in that picture as being at chest level rather than throat level. The picture is useful as an introduction to the hand signal, but it doesn't tell the whole story. This is why I prefer in-person learning. In the real world, when a diver is horizontal and swimming frantically toward you while making a slashing motion, nobody will mistake that signal for anything else. On an exam where you're presented with that picture and never discussed it further in class, sure, I suppose it's possible to be uncertain.Here's the WRSTC version from "Common Hand Signals for Scuba Diving" which is available (along with all their standards) at Standards Downloads - WRSTC
It occurs to me that if a student's goal is to achieve a perfect exam score, the student might be better off tuning out information provided by well-meaning divers until they are done with the course. The student should read the material, and answer the questions based only on what they read and not any external information. That said, if a student wants to learn more that what is in the course materials, they might end up a more knowledgeable diver but they might also risk an imperfect score. It seems to me the goal should be to become a good diver, not necessarily to achieve a perfect exam score. It's valuable knowledge that there is also a "level off" sign that could be confused with the "out of air" sign" depending on the circumstances. It's valuable knowledge to know more factors that can affect visibility than only what is explained in the course materials. If the exam score is that important to you, don't over-think the question and base your answer only on what was in the course materials.