Step 1: Concept:
Write the general catalytic cycle. A radical X takes an oxygen atom from ozone, giving XO and O2. Then XO meets a free oxygen atom and gives back X. The net result is that ozone and O turn into two O2 molecules, and X is unchanged.
Step 2: Test which pairs fit this pattern.
The pair must be a radical and its oxide. NO and NO2 fit, Cl and ClO fit, and HO and HO2 fit, since the pair acts as X and XO in a cycle with ozone and atomic oxygen.
Step 3: Test the pairs that do not fit.
CO and CO2 are a stable molecule and its end product, not a radical pair acting on ozone in the stratosphere. SO and SO2 are sulphur species that are mainly linked to aerosol, not to a main ozone cycle.
Step 4: List the verified set.
The valid set is B, C and D.
Step 5: Rule out option 1.
It has A and D only. It lacks B and C and includes A, so it fails.
Step 6: Rule out option 3.
It has A, C and D. It includes A and lacks B, so it fails.
Step 7: Rule out option 4.
It has A, D and E. It includes both wrong items and lacks B and C, so it fails.
Step 8: Accept option 2.
B, C and D only matches the verified set exactly.
Final Answer:
Option 2 is correct.
\[ \boxed{B,\ C\ \text{and}\ D} \]