**Core Concept**
Left ventricular hypertrophy (LVH) is characterized by thickening of the left ventricular wall, often due to increased afterload or hypertension. This leads to alterations in the electrocardiogram (ECG) that can be used for diagnosis.

**Why the Correct Answer is Right**
The Sokolow-Lyon criteria are a set of ECG criteria used to diagnose LVH. The criteria include a QRS complex amplitude in leads V5 or V6 of 3mm or greater, and the sum of the QRS complex amplitudes in leads V5 or V6 and the S wave amplitude in lead V1 or V2 of 35mm or greater. The sum of the QRS complex amplitudes in leads V5 or V6 and the S wave amplitude in lead V1 or V2 (SV1 + RV5 or RV6) is a key component of this criteria. When this sum is greater than 35mm, it is indicative of LVH.

**Why Each Wrong Option is Incorrect**
* **Option A:** Sokolow-Lyon criteria do not use the R wave amplitude in lead V1, but the S wave amplitude.
* **Option B:** The criteria do not specify a minimum QRS complex amplitude in lead V5 or V6 of 3mm or greater, but rather that one of the leads meets this criterion.
* **Option C:** The correct sum of amplitudes is SV1 + RV5 or RV6, not SV2 + RV5 or RV6.
* **Option D:** The correct sum of amplitudes is greater than 35mm, not 30mm.

**Clinical Pearl / High-Yield Fact**
When interpreting ECGs for LVH, remember that the Sokolow-Lyon criteria are more specific than the Cornell Voltage criteria, but less sensitive. The criteria require careful measurement of the QRS complex and S wave amplitudes in leads V1 and V5 or V6.

**Correct Answer: D. 35mm**