Answer:
d) by suggesting that Ophelia’s madness is a sign of greater troubles.
Step-by-step explanation:
William Shakespeare's Hamlet revolves around the act of a young prince's desire to avenge the death of his father, the king. The young prince Hamlet brings about many disasters along with his plan of getting revenge at the perpetrators of his father's death.
The given passage from Act IV scene v shows Queen Gertrude being told about Ophelia's madness and her constant 'babble' of things unknown and unseen. Queen Gertrude was reluctant at first to comply with Ophelia's request to be shown to the Queen. But she relented after Horatio told her it might lead to the revelation of any dangerous and evil troubles in the future. She also admitted, "Each toy seems prologue to some great amiss". This shows that she also believes it may reveal some greater hidden plots for them.
Thus, her decision to allow Ophelia to meet her advances the plot by suggesting that it's a sign of the upcoming greater troubles in the kingdom.