What is one difference between BPDU protection and root guard?

What is one difference between BPDU protection and root guard?
A . BPDU protection works with RPVST+, RSTP, and MST
B . Root guard works with RSTP or MSTP, but not RPVST+.
C . BPDU protection blocks a port if it receives any BPDU, but root guard blocks a port only if the BPDU indicates a better root path.
D . BPDU protection is typically implemented on edge ports, but root guard is typically implemented on uplinks with the root port role.
E . BPDU protection drops BPDUs received on a port, but does not block the port. Root guard blocks the port if it receives a BPD

Answer: B

Explanation:

Reference: http://ericleahy.com/index.php/bpdu-guard-bpdu-filter-root-guard-loop-guard-udld/