The boiling point of a hydride depends on several factors such as molecular weight, intermolecular forces, and polarity. Let's analyze the given hydrides to determine which one has the lowest boiling point:

(a) H2O (Water):
- Molecular weight: 18 g/mol
- Intermolecular forces: Water molecules are polar due to the electronegativity difference between hydrogen and oxygen atoms. This polarity allows for hydrogen bonding, which is a strong intermolecular force.
- Boiling point: Due to the strong hydrogen bonding, water has a relatively high boiling point of 100°C.

(b) H2Se (Hydrogen Selenide):
- Molecular weight: 80 g/mol
- Intermolecular forces: Hydrogen selenide is a polar molecule, but it has weaker intermolecular forces compared to water. It forms dipole-dipole interactions.
- Boiling point: The boiling point of H2Se is around -41°C.

(c) H2Te (Hydrogen Telluride):
- Molecular weight: 130 g/mol
- Intermolecular forces: Hydrogen telluride is also a polar molecule with dipole-dipole interactions.
- Boiling point: The boiling point of H2Te is approximately -2.2°C.

(d) H2S (Hydrogen Sulfide):
- Molecular weight: 34 g/mol
- Intermolecular forces: Hydrogen sulfide is a polar molecule that can form dipole-dipole interactions.
- Boiling point: The boiling point of H2S is -60°C.

Based on the above information, we can conclude that H2S (Hydrogen Sulfide) has the lowest boiling point among the given hydrides, with a boiling point of -60°C. This is due to its relatively low molecular weight and weaker intermolecular forces compared to the other hydrides.