**Core Concept**
In biochemistry, enzymes interact with substrates through various types of forces, enabling efficient catalysis. The enzyme-substrate complex is stabilized by these forces, which facilitate the conversion of substrates into products. Understanding the different types of forces involved is crucial for grasping enzyme-substrate interactions.

**Why the Correct Answer is Right**
Van der Waals forces are weak intermolecular forces that contribute to the binding of substrates to enzymes. However, these forces are not the primary stabilizing forces in the enzyme-substrate complex. The main forces involved are covalent, electrostatic, and hydrogen bonding. Van der Waals forces are relatively weak compared to these forces, which are essential for enzyme-substrate interactions. The enzyme-substrate complex is primarily stabilized by covalent bonds, electrostatic forces, and hydrogen bonds, which facilitate the catalytic process.

**Why Each Wrong Option is Incorrect**
**Option A:** Electrostatic forces are indeed a crucial component of enzyme-substrate interactions, as they contribute to the binding of positively and negatively charged substrate molecules to the enzyme. Electrostatic forces help position the substrate correctly for catalysis.

**Option B:** Covalent bonds are not typically a part of the initial enzyme-substrate complex. Covalent bonds are formed during the catalytic process, where the enzyme facilitates the formation of a covalent intermediate between the substrate and the enzyme. However, this is not a characteristic of the initial enzyme-substrate complex.

**Option D:** Hydrogen bonding is a critical force in enzyme-substrate interactions, as it helps position the substrate correctly for catalysis. Hydrogen bonds are formed between the enzyme and the substrate, and they play a key role in stabilizing the enzyme-substrate complex.

**Clinical Pearl / High-Yield Fact**
Remember that the enzyme-substrate complex is stabilized by covalent, electrostatic, and hydrogen bonding forces. Van der Waals forces are relatively weak and play a minor role in enzyme-substrate interactions.

**✓ Correct Answer: C. Van der waals**