Final answer:
The main physical geographic difference between the Greater Antilles and the Lesser Antilles is volcanic activity. The correct answer is B.
Step-by-step explanation:
The Greater Antilles, which include the large islands of Cuba, Jamaica, Hispaniola, and Puerto Rico, have higher mountain relief and are more prone to volcanic activity. The Lesser Antilles, on the other hand, are smaller islands and generally have lower-lying and flatter topography. The main physical geographic difference between the Greater Antilles and the Lesser Antilles is B. Volcanic activity.