The question asks:

Which compound will be most easily attacked by an electrophile?

To answer this, we must identify the compound that is most electron-rich, because an electrophile attacks regions of high electron density.

Step 1: Principle involved

Electrophilic attack is favored on compounds that:

1. have high electron density,
2. can donate electrons easily,
3. are activated by groups showing $+M$ effect or electron-releasing effect.

Compounds that are electron-deficient or contain electron-withdrawing groups are less prone to electrophilic attack.

Step 2: Problem with the given data

The options labeled A, B, C, D are not visible in the question. So the actual structures/compounds to compare are missing.

Without the structures, it is not possible to independently derive which specific option is most susceptible to electrophilic attack.

Step 3: Comparison with stored answer

The stored correct answer is B.

Since the compounds themselves are not provided, I cannot verify chemically whether B is truly correct. Therefore, I cannot confidently agree based on derivation.

Conclusion

Because the options are missing, the question is incomplete. A rigorous solution cannot be produced unless the structures for A, B, C, D are provided.