Ruby, who was driving too fast for conditions, collided with a truck carrying explosives. The truck was unmarked, so Ruby had no way of knowing what it contained. The collision caused an explosion, which shattered glass in a building a block away. The glass injured Ida, who was working inside the building. John, who was walking down the street near the site of the collision, was seriously burned as a result of the explosion. In this case:

a$.$

Ruby's negligent driving is the proximate cause of John's injury.

b$.$

both Ida and John are within the zone of danger of the collision.

c$.$

Ruby's negligent driving is the proximate cause of Ida's injury.

d$.$

the driver of the explosive truck is contributorily negligent because the truck should have been marked.