Answer:
Option D, An understory of oak trees
Step-by-step explanation:
The State and transition models of the oak woodlands are depended on the fire cycle. It is also claimed by researchers that forest fire (disturbances) are important determinants of the patchy distribution of these vegetation types in woodland.
A woodland with no or without frequent fires has an understory of oak trees comprising of native annual and perennial trees, grasses and forbs. Most of these native tree , grass, forbs and shrub species vary in amount due to inadequate fire frequency.
Hence, option D is correct