1. Identify the reaction type

Propene reacts with $HOCl$ (generated from $Cl_2 + H_2O$) to form a halohydrin.

For alkenes, the mechanism is:

• electrophilic addition of $Cl^+$ to the double bond,
• formation of a carbocation / bridged chloronium-type intermediate idea,
• then attack by water.

At the JEE level, this is commonly represented through the more stable carbocation-like intermediate formed after addition of $Cl^+$.

2. Write the alkene

Propene is:

When an electrophile adds, the intermediate should be such that the more stable carbocation is formed.

3. Apply Markovnikov orientation

If $Cl^+$ adds to the terminal carbon, the positive charge appears on the middle carbon:

This is a secondary carbocation, which is relatively stable.

If instead the positive charge were on the terminal carbon, we would get a primary carbocation, which is less stable.

So the preferred intermediate is:

4. Match with options

• A: $\mathrm{CH_3-CH^+-CH_2OH}$ — not the intermediate formed immediately after electrophilic attack.
• B: $\mathrm{CH_3-CHCl-CH_2^+}$ — primary carbocation, less stable.
• C: same as A in written form.
• D: $\mathrm{CH_3-CH^+-CH_2Cl}$ — correct.

5. Final answer

The intermediate is:

So the correct option is D.

6. Comparison with stored answer

Stored correct answer: D

My derived answer: D

They agree.