The boiling point elevation constant $K_b$ is also known as:

Ebullioscopic Constant

The correct answer is Option (3) → Ebullioscopic Constant

Quick Explanation:

• Boiling Point Elevation Constant ($K_b$): It is the constant used in the formula for elevation of boiling point ($ΔT_b = K_b × m$), where m is molality.
• It is also called the Ebullioscopic Constant (from "ebullioscopy," meaning measurement of boiling points).

Why others are wrong:

1. Cryoscopic Constant: This is $K_f$, used for freezing point depression ($ΔT_f = K_f × m$).
2. Molar Depression Constant: This refers to $K_f$ (freezing point depression), not boiling point elevation.
3. Boiling Constant: Not a standard term; it's just a vague name.