The correct answer is: A. Jena glass.
Jena glass is a type of optical glass that is used in making lenses and prisms. It is a borosilicate glass that is known for its high refractive index, low thermal expansion, and chemical durability. Jena glass is also known for its high optical quality, which makes it ideal for use in precision optical instruments.
Soft glass is a type of glass that is made from soda ash, lime, and silica. It is a relatively low-melting glass that is easy to work with. Soft glass is often used in making light bulbs, glassware, and other objects that do not require a high degree of optical quality.
Pyrex glass is a type of borosilicate glass that is known for its high thermal resistance. It is often used in making cookware, laboratory equipment, and other objects that need to withstand high temperatures. Pyrex glass is not as optically pure as Jena glass, so it is not typically used in making lenses and prisms.
Flint glass is a type of lead glass that is known for its high refractive index and dispersion. It is often used in making optical instruments, such as lenses and prisms. Flint glass is also used in making decorative objects, such as vases and chandeliers.