The correct answer is letter B.
Explanation: The Patellar Reflex is a monosynaptic reflex arc.
Interneuron does not make part of the pathway to contraction of the muscle. The sensory neuron synapses from a motor neuron in the spinal cord.
An effector is a muscle that receives the impulse from the motor neuron. In somatic reflexes, the effector is skeletal muscle. In autonomic (visceral) reflexes, the effector is smooth or cardiac muscle, or a gland.