Final answer:
In the context of the nervous system, white matter consists mainly of myelinated axons which facilitate communication between gray matter areas within the CNS. The correct answer to what type of connection allows this is 'Axon' (option b), as it forms the white matter pathways for signal transmission.
Step-by-step explanation:
White matter is a type of nervous tissue found in the central nervous system (CNS) which comprises mainly myelinated axons. The myelin sheath, a lipid-rich substance, gives white matter its characteristic white appearance due to its high lipid content. Gray matter, on the other hand, mainly contains the cell bodies of neurons and is typically found in regions where processing and synaptic connections occur.
With regard to the question, the tissue through which messages pass between different areas of gray matter within the nervous system is indeed white matter. The correct answer to which connection facilitates this communication is 'b. Axon,' since axons are covered with myelin sheath and make up the white matter, transmitting signals across different parts of the CNS and to the body through peripheral nervous system connections.
Synapses are located in the gray matter, and though they play an essential role in the transmission of signals, they are not the connections referred to in this context. Dendrites are also involved in receiving signals but are not the white matter pathways in question. Myelin is the insulating layer that enables the rapid transmission of signals but does not constitute the connective pathway itself.