Which is a physical sign of cannabis use?

The presence of rolling papers is indeed an indicator of potential cannabis use, as they are commonly associated with the preparation and consumption of cannabis. Rolling papers are a practical tool that many users keep on hand for joint-making, which is a typical method of using cannabis. This physical item serves as a tangible clue that aligns with the behavior surrounding cannabis consumption.

The other options relate to behavioral or physiological responses that are less definitive as physical signs of cannabis use. Heavy breathing and rapid speech could be influenced by various factors, not exclusively cannabis. While increased heart rate is a physiological response that may occur with cannabis consumption, it can also be associated with other substances or conditions. Thus, rolling papers serve as a more direct and identifiable physical sign of cannabis use.