Let A={1,2,3} and B={4,5,6}. Which one of the following functions is bijective?

• A. f={(2,4),(2,5),(2,6)}
• B. f={(1,5),(2,4),(3,4)}
• C. f={(1,4),(1,5),(1,6)}
• D. f={(1,4),(2,5),(3,6)}