The anterior portion of the body of most annelids, such as the earthworm, is adapted for sensing the environment.
a. true
b. false

The answer is False. Although sensitive cells are more abundant in the anterior portion of the annelid´s body, in general, they are arranged in all the segments.

Explanation:

Annelids, such as the earthworm, have a variety of sensory cells:    

Mechanoreceptors, disposed of in groups in each segment of their body.  Photoreceptors: Light-sensitive cells. Although they are located in the whole body, they are abundant in anterior and posterior segments, concentrated in the intern and dorsal part of the epidermis.Humidity receptors are the most sensitive cells and are located in the first segments of the earthworm bodyChemoreceptors: sensorial cells cumulus forming a prominent tubercle with prolongations that extends through the cuticle. These tubercles form three rings in each segment but are especially abundant in the anterior part of the body.

The tegument is very rich in free nervous terminations, which functions might be tactile.

Mitochondria is the cell organelle that produced the energy that is needed in the body system in form of atp, that is why it is called the power house of the cell. energy is needed by the living organisms to carry out the activities which sustain life.  if the mitochondria is destroyed atp will not be produced. if the mitochondria is destroyed, energy production will stop and the affected living organism will not have the energy to carry out the necessary life processes; this will lead to the death of the organism.