Which characteristic describes ease of manufacturing and cost effectiveness?

• A. Safe
• B. Optically regular
• C. Durable
• D. Easily and inexpensively manufactured

Answer: (D)

Manufacturing feasibility and cost-effectiveness hinge on how readily a material can be processed into lenses and how expensive that processing is. The option that says the material is easily and inexpensively manufactured directly addresses both how easy it is to produce and how low the production costs will be, which is what engineers and manufacturers care about during material selection. Safety ensures biocompatibility, optical regularity ensures clear vision, and durability concerns how long the lens lasts; none of these by themselves guarantee easy production or low cost, so they don’t match the prompt as well as the explicit statement about ease and cost.