In an Experiment, Mutation of Bases at the Very 5

In an experiment, mutation of bases at the very 5' end of the togavirus genome reduces the amount of the negative-strand of the genome produced.What does this result suggest?

A) That the virus genome contains an IRES sequence.
B) That the packaging sequence is only found at the 5' end of the genome.
C) That the replication complex binds to both ends of the genome.
D) That the genome forms a covalently closed circle for replication.
E) That a protein is used as a primer for genome replication.