The correct answer is option B
The evolutionary development that can be seen in annelids is the pressence of true coelom. It can be defined as the body cavity which is a fluid filled body cavity lined with the mesodermal tissues.
It provides the space inside the body for the development of other organs and to get attached to the body.
The fluid that is present in the coelom acts as shock absorber to prevent the organism from external shocks.