How do aromatics influence key fuel quality metrics in diesel, kerosene, and petrol (gasoline)? Select the correct statement.

Introduction:
Aromatic content affects combustion properties differently across fuels. Understanding these trends is vital for meeting specifications and engine performance requirements.

Given Data / Assumptions:

• Three fuels considered: diesel, kerosene, petrol (gasoline).
• We seek the correct directional effect of aromatics on standard quality metrics.

Concept / Approach:
Aromatics tend to lower diesel cetane number (poorer ignition quality), lower kerosene smoke point (more sooting), and raise gasoline octane (improved knock resistance).

Step-by-Step Solution:
1) Diesel: aromatics lower cetane → statement “increase cetane” is false.2) Kerosene: aromatics lower smoke point → statement “increase smoke point” is false.3) Petrol: aromatics raise octane → statement is true.

Verification / Alternative check:
Fuel property tables and specs consistently document these trends; reformate rich in aromatics often boosts gasoline octane, while diesel specs limit aromatics to preserve ignition quality.

Why Other Options Are Wrong:
Option a: Direction is reversed for diesel.Option b: Direction is reversed for kerosene smoke point.Option d: Combines incorrect statements.Option e: Contradicts gasoline octane behaviour.

Common Pitfalls:
Generalizing a single effect of aromatics across all fuels; each metric responds differently because of engine and combustion mode differences (SI vs CI).

Final Answer:
In petrol, aromatics increase octane number.