What is the best explanation for the speciation event that produced the wild sunflower Helianthus anomalis?

A)hybridization of two sunflower species where natural selection produced extensive genetic changes, but with no change in chromosome number
B)hybridization of two sunflower species where natural selection produced extensive genetic changes with duplication of chromosomes
C)hybridization followed by asexual reproduction
D)gradual speciation that occurred over millions of years
E)allopolyploid speciation