What is the primary hazard of carrying unsecured bulk grain or agricultural produce in an open-topped truck without tarpaulins in Cameroon?

1. Spillage onto the roadway creates slipping hazards for two-wheelers, flying debris impairs trailing vehicles, and cargo shifting causes vehicle rollover
2. Grain absorbs air nitrogen and explodes spontaneously
3. The grain attracts radio interference from telephone poles
4. The weight of grain doubles every hour of driving