Final answer:
The question provided does not include the correct excerpt from Twelfth Night about Olivia's seclusion. The right lines are from Valentine in Act 1, Scene 1, stating Olivia will mourn her brother's death in private for seven years.
Step-by-step explanation:
The excerpt from act one of Shakespeare’s Twelfth Night that informs the audience about Olivia's self-imposed seclusion is not provided in the given excerpts. The relevant line occurs later, when Valentine reports Olivia’s intention to sequester herself to mourn her brother's death:
“The element itself, till seven years' heat, Shall not behold her face at ample view; But, like a cloistress, she will veiled walk And water once a day her chamber round With eye-offending brine” (Act 1, Scene 1).
Olivia’s decision to mourn is a significant plot point, as it sets the stage for the romantic entanglements that follow.