Answer: Option (a) is the correct answer.
Explanation:
The given sign in the picture is a large image and usually these signs are used on roads in order to alert people that trucks are also passing through so everyone must drive carefully in order to avoid any accident.
These signs are basically caution symbols framed for the safety of people.
Whereas a sign with no trucks on this roadway will have a cross sign on the picture of a truck.
Thus, we can conclude that the given picture mean that be aware of large trucks on the roadway.