If you have two objects which are plural (e.g. apples and oranges) and a non-restrictive relative clause, to which does the relative clause refer? E.g.:
He noticed the apples and oranges, which were rotting, in the room next door.
Are the apples rotting? The oranges? Both? Is this statement clear or ambiguous?
If you tried to restrict the relative clause only to "oranges":
He noticed the apples and oranges (that were browning) in the room next door.
Is that not an improper "that," since it is non-essential? Does it still appear ambiguous? What is the proper protocol on this?