The traffic is so heavy. It will take us at least an hour to get there. Unless the traffic is heavy, it will take us at least an hour to get there. As the traffic is so heavy, it...

A. Unless the traffic is heavy, it will take us at least an hour to get there.

B. As the traffic is so heavy, it will take us at least an hour to get there,

C. The traffic was so heavy that it took us an hour to get there.

D. We will spend more than an hour to get there to avoid heavy traffic.