An adjuster accepts a late proof of loss, inspects the damage and negotiates for weeks, then denies the claim because the proof was late. The insurer is most likely barred by:

Explicación

Waiver is the voluntary giving up of a known right, and estoppel prevents a party from taking back a position that the other side reasonably relied on to its detriment; by handling the claim as though the late proof were acceptable, the insurer gave up that defense. Adhesion is described backwards here, because ambiguous wording drafted by the insurer is construed against the insurer and in favor of the insured.