Final answer:
Statement B, which mentions the invaders having more pulling power due to animals like horses, oxen, and donkeys, indicates an increase in labor efficiency in the New World as a result of the Columbian Exchange.
Step-by-step explanation:
The impact of the Columbian Exchange on the efficiency of labor in the New World is highlighted by the introduction of large draft animals such as horses, oxen, and donkeys, which were not originally present in the Americas. These animals significantly improved the efficiency of labor by providing additional pulling power necessary for tasks like plowing fields and moving heavy loads, which had previously been much more labor-intensive. Statement B, 'The invaders had more pulling power - not only horses but also oxen and donkeys.', indicates this profound change. Additionally, the introduction of the wheel, widely used in Europe but not known in the pre-Columbian Americas, further revolutionized transportation and agricultural practices.
Before the arrival of Columbus, native populations relied on human labor to perform these tasks, which was significantly less efficient. The newly introduced animals and technologies not only shaped the social and economic structures within the colonies but also had far-reaching implications on the development of the New World, propelling agricultural productivity and contributing to the exploitation of its vast natural resources.