Flammable and combustible liquids are defined as liquids with a flashpoint of what temperature or lower?

The correct choice is based on the definitions established for flammable and combustible liquids. A flammable liquid is typically defined as having a flashpoint of 37.8 degrees Celsius (100 degrees Fahrenheit) or lower, while a combustible liquid has a flashpoint above that temperature but not exceeding 60.5 degrees Celsius (140 degrees Fahrenheit). Since the question specifically asks for liquids with a flashpoint of "what temperature or lower," the temperature of 60.5 degrees Celsius applies specifically to the upper limit of combustible liquids.

Thus, 60.5 degrees Celsius identifies the transition point where a liquid would still be considered combustible, making it crucial for safety regulations and handling procedures in various industries. This distinction supports safe storage, usage, and transport in environments where these liquids may be present.