**Core Concept**
Nephrotic syndrome is a collection of symptoms due to kidney damage, specifically to the glomeruli, leading to severe loss of protein in the urine. This condition involves **glomerular injury**, resulting in **heavy proteinuria**. The key features of nephrotic syndrome are related to the loss of large amounts of protein and the body's response to this loss.

**Why the Correct Answer is Right**
The correct answer includes **Massive Proteinuria**, which is defined as the excretion of more than 3.5 grams of protein per 1.73m^2 body surface area per day. This is a hallmark of nephrotic syndrome, as it indicates significant damage to the glomerular filtration barrier. Other components of the definition include **Hypoalbuminemia**, **Hyperlipidemia**, and **Edema**.

**Why Each Wrong Option is Incorrect**
**Option A:** Microalbuminuria refers to the excretion of small amounts of albumin in the urine and is an early sign of kidney damage, especially in diabetic patients, but it is not part of the definition of nephrotic syndrome.
**Option C:** Microscopic hematuria, or the presence of blood in the urine visible only under a microscope, can occur in various kidney and urinary tract disorders but is not a defining feature of nephrotic syndrome.

**Clinical Pearl / High-Yield Fact**
Remember that nephrotic syndrome is characterized by the loss of large amounts of protein, leading to hypoalbuminemia, which in turn causes edema and hyperlipidemia due to increased hepatic production of lipids.

**Correct Answer:** B. Massive Proteinuria