Read the following passage: "The concept of continental drift, proposed by Alfred Wegener in the early 20th century, initially faced significant skepticism. Wegener gathered evidence such as the 'jigsaw puzzle' fit of continents, matching fossil records across oceans, and similar rock formations on widely separated landmasses. However, he lacked a plausible mechanism to explain *how* continents could move. It wasn't until the development of plate tectonics theory in the mid-20th century, which introduced the idea of convection currents in the Earth's mantle, that a comprehensive explanation for continental movement became widely accepted. Plate tectonics not only validated Wegener's observations but also provided the missing 'engine' for continental motion." What was the primary reason continental drift was not initially accepted, despite Wegener's evidence?

1. AThere was insufficient fossil evidence to support his claims.
2. BHe could not explain the mechanism by which continents moved.
3. CHis theory failed to account for oceanic trenches.
4. DThe 'jigsaw puzzle' fit of continents was considered coincidental.