This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Bacteriology, Subject name: Microbiology
A person has received complete immunization against tetanus 10 years ago. Now he presents with a clean wound without any lacerations from an injury sustained 2.5 hours ago. He should now be given 
Select and explain. 
A. Full course of tetanus toxoid, B. Single dose of tetanus toxoid, C. Human tet globulin, D. Human tet globulin and single dose of toxoid
B: Single dose of tetanus toxoid
Answer: B: Single dose of tetanus toxoid 
Explanation: Active immunisation is not only the most effective method of prophylaxis but also the only means whereby tetanus following unnoticed injuries can be prevented. This is achieved by spaced injection of formol toxoid, which is available either as plain toxoid or adsorbed on aluminium hydroxide or phosphate. A full course of immunisation confers immunity for a period of at least ten years. A booster dose of toxoid is recommended after 10 years. A booster dose of toxoid is given if wounding occurs three years or more after a full course of immunisation. Reference: Textbook of Microbiology; Anathanarayan and paniker&;s; 9th edition; Page no: 262, 263