What type of argument is the following argument? The brains of rats raised in enriched environments with a variety of toys and puzzles weigh more than the brains of rats raised in more barren environments. Therefore, the brains of human brains will weigh more if humans are placed in intellectually stimulating environments.
A、Reasoning by principle.
B、Reasoning by definition.
C、Reasoning by analogy.
D、Reasoning by generalization.