When driving a Category C truck at night, why should you exercise extreme caution when passing parked trucks along roadside shoulders in Cameroon?

1. Parked trucks often lack functional reflectors, frequently have mechanics working underneath in the roadway, or may project unlit cargo into active travel lanes
2. Parked trucks emit radar signals that disable engine ignition systems
3. Parked trucks cause passing vehicle air conditioning compressors to fail
4. Parked trucks are always used as temporary police speed traps