Adding surfactants in non polar solvent, the micelles structure will look like
(a)

(b)

(c)

(d)

A surfactant molecule consists of two parts:

• A polar (hydrophilic) head
• A non-polar (hydrophobic) tail

The arrangement of surfactant molecules depends on the nature of the solvent.

In a polar solvent such as water, the polar heads interact with the solvent, while the non-polar tails remain away from it. Hence, the tails aggregate towards the center, forming normal micelles.

In a non-polar solvent, the arrangement is reversed. The non-polar tails interact readily with the non-polar solvent and point outward, whereas the polar heads avoid contact with the solvent and cluster together at the center.

Such an arrangement is called a reverse micelle.

Since the question involves a non-polar solvent, the surfactant molecules will form reverse micelles with:

• Polar heads directed inward
• Non-polar tails directed outward

Among the given diagrams, only diagram (a) represents this arrangement.

Hence, the correct answer is

$$\boxed{\text{Diagram (a)}}$$