A paramount scientific finding by Mark Rosenzweig found that, compared to control rodents, rodents raised in enriched environments had:

a. increased cortical mass, increased numbers of neurons, increased synaptic connections, increased neurotransmitter amounts, and increased myelination.
b. increased cortical mass, increased numbers of neurons but decreased synaptic connections, decreased neurotransmitter amounts, and decreased myelination.
c. decreased cortical mass, decreased numbers of neurons yet increased synaptic connections, increased neurotransmitter amounts, and increased myelination.
d. decreased cortical mass, decreased numbers of neurons, decreased synaptic connections, decreased neurotransmitter amounts, and decreased myelination.

The correct option is a. "increased cortical mass, increased numbers of neurons, increased synaptic connections, increased neurotransmitter amounts, and increased myelination. "

Explanation:

Rodents that have been raised in enriched environments were found to have thicker cerebral cortex containing approximately 25% more synapses in a study conducted by Mark Richard Rosenzweig. This increase in synapses implies in an increase in neurons and neurotransmitters, which also indicates an increase in myelination.