Final answer:
The only safe type of pencil to use on a client is b) One with a felt tip, as it reduces the risk of skin injury and promotes better hygiene.
Step-by-step explanation:
When using pencils on clients, particularly in contexts such as makeup or skin marking in medical settings, safety and hygiene are paramount. The correct answer to the question is b) One with a felt tip. This type of pencil is less prone to causing accidental injury due to its softer tip. A felt tip pencil, being less sharp than traditional pencils, minimizes the risk of puncturing the skin or causing scratches.
It is also disposable which can ensure better hygiene compared to a pencil that can be sharpened, potentially harboring bacteria. On the other hand, options a) and c) could pose potential hazards if they become too sharp, while d) does not specify a safety feature relevant to the question.