What is the effect of configuring the following command on a switch?

What is the effect of configuring the following command on a switch?

Switch(config)# spanning-tree portfast bdpufilter default
A . If BPDUs are received by a port configured for PortFast, then PortFast is disabled and the BPDUs are processed normally.
B . If BPDUs are received by a port configured for PortFast, they are ignored and none are sent.
C . If BPDUs are received by a port configured for PortFast, the port transitions to the forwarding state.
D . The command enables BPDU filtering on all ports regardless of whether they are configured for BPDU filtering at the interface level

Answer: A