Final answer:
You should wear a full-length lab coat in designated areas which, in most cases, means whenever you are in the laboratory to protect against potential hazards.
Step-by-step explanation:
The correct answer to the question "When do you have to wear a full-length lab coat?" is: C) In designated areas. It's important to follow lab safety protocols, which typically require wearing a full-length lab coat in specified areas to ensure your safety and the safety of others. During lab sessions, this would most commonly mean always in the lab, unless otherwise indicated.
Wearing a full-length lab coat is part of standard laboratory safety guidelines to protect against spills, splashes, or contamination. Other garments you should wear in a science lab that you would not usually wear outside include safety goggles, gloves, and sometimes a face shield, depending on the nature of the lab work. Additionally, you should secure loose clothing and tie back long hair to prevent accidents, particularly when working near open flames or heating elements.