Reasonable Care is a duty held by both individuals and businesses, to provide reasonable care in their actions. Unreasonable actions that result in injury may be a cause for a negligence claims.
In the case of an individual, Reasonable Care requires a driver to stop at a red light. If the driver runs the red light and causes an accident with injuries, she may well be found liable.
For a business, suppose a customer drops a bottle of wine at a grocery store and informs the manager of the store. If the manager does not clean up the mess in a reasonable time, and another customer slips on the liquid and is injured, the business is liable.