Answer:
Based on the information provided, the expanded stage direction most likely reveals that Young Siward does not have the ability to defeat Macbeth (answer B). The stage direction "Young Siward falls" suggests that he is overpowered by Macbeth in a sword fight, and is unable to defeat him. It is not explicitly stated in the stage direction whether or not Young Siward has had intense training in sword fighting or whether he is someone who gives up easily.
Step-by-step explanation: