Which of the following factors could have contributed to his AOM?

A 4-year-old boy has had otitis media with effusion (OME) for several weeks and his condition has recently progressed to acute otitis media (AOM). Which of the following factors could have contributed to his AOM?
Reflux of fluid from the boy’s nose into his middle ear
A deficiency in immunoglobulin G
Accumulation of cerumen in the external acoustic meatus
Sensorineural deficits in the auditory control apparatus
Exposure to respiratory syncytial virus (RSV)