Police Have Corroborated Information That a Mobile Home,the Residence of Ernst,was

Police have corroborated information that a mobile home,the residence of Ernst,was being used as a distribution point for illicit drugs.The trailer was hooked to utilities and septic system in a mobile home lot and was elevated on blocks.The truck which towed the vehicle was parked nearby.If officers immediately knock and announce,enter,and conduct a warrantless search without consent,the search will be

A) invalid because they do not have a warrant.
B) valid because the mobile home was readily mobile.
C) invalid because the officers did not have knowledge that the evidence would be destroyed if they delayed.
D) valid because of exigency.