What does an Accept signal protect?

An Accept signal is primarily used to ensure the safe passage of a train by indicating that it is permitted to enter a block that is under the control of a home signal. Specifically, it protects the block on approach to a home signal, meaning that it allows the train to proceed with caution while ensuring that any potential conflicts or hazards within that block are managed appropriately. The purpose is to maintain safety and efficiency in train operations, especially as the train approaches the home signal which will dictate its final stop or continuation.

In the context of the other options, protecting the neutral zone or the block ahead would not accurately reflect the primary function of an Accept signal. Similarly, while it is important to manage the entirety of the track section, the Accept signal's main role is focused specifically on the block approaching the home signal. This careful control helps prevent accidents and ensures orderly train movements on the network.