What is the result of enabling spanning-tree portfast on an access port?

Enabling spanning-tree portfast on an access port allows the port to bypass the usual Spanning Tree Protocol (STP) listening and learning states, allowing it to transition directly to the forwarding state. This is particularly useful for access ports that are connected to end devices, such as computers or printers, which do not send bridge protocol data units (BPDUs). Since these devices typically do not participate in the spanning tree and the port is not expected to form any network loops, the immediate transition to the forwarding state helps in reducing the time it takes for devices to start communicating on the network.

The other options do not accurately describe the behavior of a port when portfast is enabled. There is no requirement for manual shutdown or a restriction to only BPDU traffic, nor does the port shut down upon receiving a frame. The primary function of portfast is to expedite the port's readiness to transmit and receive traffic, streamlining the connection process for devices connected to the port.