Concept:Hibiscus and croton are ornamental shrubs that are commonly planted in rows to create living fences or boundaries.
Explanation:Hibiscus and croton grow as dense, woody shrubs that can be pruned into a compact shape.
They are often planted closely together along compound edges to form a protective barrier.
This use is exactly what defines a hedge plant.
Ground covers spread low over the soil surface and do not form a vertical boundary.
Lawn plants are grasses meant for mowing, not shrubs.
Avenue trees are tall trees planted along roads, which hibiscus and croton are not.
Therefore, the correct classification is hedge plants.
Answer:B. hedge plants