Final answer:
Rolling up one's shirtsleeve indicates implied consent for a venipuncture procedure, as it shows the patient is preparing for and willing to undergo the procedure.
Step-by-step explanation:
An implied consent for venipuncture, indicated by a patient's action, would be rolling up his shirtsleeve. This non-verbal communication suggests that the patient is preparing for the procedure and is offering the site for venipuncture. Although expressing concerns or asking questions might be indicative of the need for further discussion, it is the act of making the area accessible for the procedure that demonstrates implied consent.