[Red Herring]

Potentially you might try and shift some responsibility onto the driver of car B as it was their actions that compromised your ability to deal with the developing situation in front of you, however the fact that the bike still stopped before running into the vehicle ahead does tend to suggest rider incompetence was mainly to blame (bikes tend to stop better whilst upright on their tyres rather than sliding on their fairings......)

Why did car A hit the brakes?