What is a possible explanation for why ssDNA viruses have genomes less that 10kb in size?

A) ssDNA is not as physically stable as dsDNA.
B) ssDNA is not transcribed by host cells.
C) ssDNA can form hairpin structures because of base-pairing.
D) Larger pieces of ssDNA can not be replicated.
E) Larger pieces of ssDNA can not easily enter the host cell.