Final answer:
The correct option is A. The character from 'Macbeth' who fits the description of serving in the king's army, receiving witches' prophecies, and being killed by Macbeth is Banquo, a general who is Macbeth's friend and whose descendants are prophesied to be kings.
Step-by-step explanation:
The character in Shakespeare's Macbeth who served in the king's army, received prophecies from the witches, and was eventually killed by Macbeth is Banquo. Banquo is a fellow general and companion to Macbeth. Both characters encounter the witches together, and the witches prophesy that while Macbeth will become king, it will be Banquo's descendants who will inherit the throne in the long term.
Macbeth, consumed by his growing ambition and the desire to secure the throne for his own descendants, decides to have Banquo murdered. Banquo is indeed killed, but his son, Fleance, escapes, leaving the possibility of the prophecy's fulfillment open.