The question asks about the type of glass that is commonly used in doors and windows. Let's evaluate each option given:

• Flint Glass: This type of glass is known for its high refractive index and is primarily used in optical lenses and decorative glassware. It is not commonly used in construction applications such as doors and windows.
• Lead Glass: Also known as crystal glass, lead glass is mainly used for decorative items and in optical components. Its heavy and costly nature makes it unsuitable for common architectural applications like doors and windows.
• Borosilicate Glass: Known for its thermal resistance, this type is commonly used in laboratory glassware and cookware. While it is durable, it is not the standard choice for doors and windows due to cost considerations.
• Soda-lime Glass: This is the most common type of glass used for doors and windows. It is affordable, can be easily formed into sheets, and maintains excellent clarity. Its composition includes about 70-75% silica, with a mix of soda (Na₂O) and lime (CaO), which reduces the melting point for fabrication.

Based on the above evaluation, Soda-lime glass (option D) is the correct answer as it is widely used in the production of windows and doors due to its cost-effectiveness and suitable physical properties.