Switches use STP to prevent loops by causing some interfaces to block, meaning that they do not send or receive frames.

(A) TRUE
(B) FALSE

TRUE is the correct answer. A primary feature of LAN switches is loop prevention, as implemented by Spanning Tree Protocol (STP). Without STP, any flooded frames would loop for an indefinite period of time in Ethernet networks with physically redundant links.

To prevent looping frames, STP blocks some ports from forwarding frames so that only one active path exists between any pair of LAN segments. The result of STP is good: frames do not loop infinitely, which makes the LAN usable. However, STP has negative features as well, including the fact that it takes some work to balance traffic across the redundant alternate links.