The type of glass used in making lenses and prisms is:
a.) A flint glass
b.) Jena glass
c.) Pyrex glass
d.) Quartz glass

Hint: In the optical glass industries, the flint glass is a highly refractive lead-containing glass and it absorbs most ultraviolet light and is comparatively little visible. It is suitable for making lenses and prisms.
Complete step-by-step answer:
We have been asked the type of glass used in making lenses and prisms.
So, first discuss lens and prism.

Lens-
A piece of glass or other material which is transparent and has curved sides for concentrating or dispersing light rays is called a lens. A lens can focus light to form an image. There are concave lenses, convex lenses, Plano-concave and plano-convex lenses and many other types of lenses available.

Prism-
A prism is a solid geometrical figure whose two ends are similar, and parallel rectilinear figures, and whose sides are parallelograms. An optical prism is a transparent optical element with flat, polished surfaces that reflect light. It is used for dispersing light into a spectrum.

Now, we have discussed lenses and prisms.
Now, in the optical industry the best suitable glass for making a prism and lenses is a flint glass.
A flint glass is a highly refractive lead-containing glass and it absorbs the ultraviolet light, but is comparatively little visible.
Hence, the correct option is A.

Note – Whenever such types of questions appear, then you should first discuss the lenses and the prisms, about their shapes and their properties, as mentioned in the solution. Also, the type of glass used for making prisms and lenses is a flint glass due to its properties like absorbing ultraviolet light and highly refractive.