Final answer:
The existence of the draft horse can be attributed to artificial selection, where humans selectively bred horses for their size and strength.
Step-by-step explanation:
The force that most likely led to the existence of the draft horse is artificial selection. Humans selectively bred draft horses over generations for their size and strength, resulting in the large and powerful horses we see today. By choosing to breed larger individuals, humans influenced the genetic makeup of the horse population.
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