which of the following is regarding the net operating loss of a trusts or estate?

which of the following is regarding the net operating loss of a trusts or estate?

1. It may require revised K-1s to be given to beneficiaries when the loss is carried back to a prior year
2. It must always be carried forward as no carryback is allowed
3. it can only arise for the operation by the trust or estate of a trade or business
4. it must be carried back by filing an amended for 1041 for the affected years