Typical features of E2 involve :

Options

A. Two step reaction
B. Second step is the rate determining step
C. Anti-periplanar transition state
D. Formation of a carbanion intermediate, stabilized by conjugation with a strong -M group.

Explanation

To answer the question regarding the typical features of E2 reactions, let's analyze the options provided step by step.

### Step-by-Step Solution:

1. **Understanding E2 Mechanism**:
- E2 (bimolecular elimination) is a type of elimination reaction that occurs in a single concerted step. This means that the bond-breaking and bond-forming processes happen simultaneously.

2. **Evaluating the Options**:
- **Option 1: Two-step reaction**:
- This is incorrect. E2 reactions occur in a single step, not two steps. Therefore, this option does not describe E2 correctly.

- **Option 2: Second step is the rate determining step**:
- This is also incorrect. In E2 reactions, there is no second step; the reaction is concerted, and the rate depends on both the substrate and the base. Hence, there is no rate-determining step as seen in E1 reactions.

- **Option 3: Anti-periplanar transition state**:
- This is correct. In E2 reactions, the leaving group must be anti-periplanar to the hydrogen atom that is being removed from the adjacent carbon. This arrangement is crucial for the formation of the double bond.

- **Option 4: Formation of a carbon ion intermediate stabilized by conjugation with a strong -M group**:
- This is incorrect. E2 does not involve the formation of a carbocation intermediate. Instead, it is a one-step mechanism without intermediates.

3. **Conclusion**:
- The correct feature of E2 reactions is **Option 3: Anti-periplanar transition state**.

### Final Answer:
The typical features of E2 involve: **Anti-periplanar transition state**.

---