The main objection to Wegner's theory of Continental Drift was ________. a. the ocean basins show no evidence of opening and closing. b. the tracks of the moving continents could not be identified on the ocean floor. c. Wegner's gravitational mechanism for the movement of continents would also stop the Earth's rotation, which has not happened. d. clear evidence of land bridges, like the one connecting Alaska and eastern Russia, clearly exist and explain most of Wegner's observations without Continental Drift.

d. clear evidence of land bridges, like the one connecting Alaska and eastern Russia, clearly exist and explain most of Wegner's observations without Continental Drift.

Explanation:

The correct answer for the given question is d. clear evidence of land bridges, like the one connecting Alaska and eastern Russia, clearly exist and explain most of Wegner's observations without Continental Drift.

The main objection to Wegener's hypothesis was his inability to identify a credible mechanism for continental drift.

Harold Jeffery pointed out that Wegener's proposition of the gravitational forces was not correct and that instead of breaking up land it would have brought Earth's rotation to halt in a matter of years.