To match the items in List-I with those in List-II, let's understand the primary associations between them:

(A) Schwann cells

Schwann cells are responsible for producing the myelin sheath around the axons of peripheral neurons. Therefore, they should match with:

(III) Myelin sheath

(B) Synaptic knob

The synaptic knob is part of a neuron where neurotransmitters are stored and released. Hence, it should match with:

(I) Neurotransmitter

(C) Bipolar neurons

Bipolar neurons are typically found in sensory structures such as the retina of the eye. Hence, they should match with:

(IV) Retina

(D) Multipolar neurons

Multipolar neurons are commonly found in the cerebral cortex of the brain. So, they should match with:

(II) Cerebral cortex

Thus, the correct matches should be:

A-III, B-I, C-IV, D-II

The correct answer is:

Option A: A-III, B-I, C-IV, D-II