In Which of the Following Situations Would Speciation Be Most

In which of the following situations would speciation be most likely to occur?

A) A population of juniper shrubs is split in two by a canyon.Every year,strong winds carry a small amount of the shrub's pollen across the canyon.
B) Seven monkeys escape from an amusement park and zoo in South Florida.To everyone's surprise,they establish a small but viable population,coexisting successfully with humans in a partly suburban environment very different from their native African habitat.
C) Bighorn sheep occupy mountains from Canada through Death Valley in Southern California,interbreeding all the way.The populations at the two ends of the range live in very different environments.
D) A Japanese mollusk species whose larvae are often carried from port to port in ship bilge water now flourishes in San Francisco Bay,a busy commercial port.