In these imprinted cells, the SNRPN transcript overlaps with another gene, called UBE3A, which is transcribed in the opposite direction. This means that the region that the RNA polymerase transcribes in these two genes actually overlaps; in some cases, overlapping transcription in opposite directions leads to transcriptional interference, meaning that collisions between the polymerases traveling in opposite directions can interfere with transcription. It is believed that this takes place in this case, meaning that the more SNRPN transcription occurs, the more this disrupts transcription of UBE3A. Based on this information as well as information about the effects of imprinting on SNRPN transcription, which of the following statements about UBE3A transcription would be true? a. The maternal copy of UBE3A is expressed and the paternal copy is silenced.
b. The paternal copy of UBE3A is expressed and the maternal copy is silenced.
c. Both copies of UBE3A are highly expressed.
d. Both copies of UBE3A are silenced.