Concept:Swollen shoot disease of cocoa is a viral infection that is spread by insect vectors that feed on the plant sap.
Explanation:The disease is caused by a virus that cannot move from tree to tree by itself.
It depends on sap-sucking insects to carry it from infected cocoa plants to healthy ones.
Among the listed options, the mealybug is the confirmed vector responsible for transmitting swollen shoot disease.
When a mealybug feeds on an infected cocoa tree, it picks up the virus.
When the same mealybug feeds on a healthy cocoa tree, it passes the virus into that plant.
Stem borers, whiteflies, and scale insects are not the main transmitters of this disease.
Therefore, the correct answer is the mealybug.
Answer:B. mealybug