Final answer:
Fingerprints are the most common method of human identification due to their uniqueness to every individual and their use in varied fields such as forensics and personal security. The correct option is c.
Step-by-step explanation:
The most common means of human-to-human identification are fingerprints. Fingerprints are unique to every individual, excluding identical twins, and remain unchanged throughout one's life. They have been widely used in various fields such as criminal investigations, forensics, and personal identification.
Additionally, fingerprint patterns are complex and varied across the globe, though not associated with race. The process of fingerprinting can involve techniques like PCR to amplify unique areas of DNA from small samples of blood, skin, saliva, or semen for identification purposes, as shown in images depicting the principle behind this method. The correct option is c.