Institution: Bangladesh Bank Exam: সমন্বিত ৪ ব্যাংক - সহকারী প্রোগ্রামার - 25.09.2020 ||
Topic: International General Knowledge, Subject: International GK (আন্তজার্তিক বিষয়াবলী)

Best Answer Explained in Below-:

While the answer provided as "B) Polyvinyl chloride" is a common misconception, it's important to clarify the materials typically used in contact lens manufacturing. The most common materials for soft contact lenses are hydrogels and silicone hydrogels, which are specifically designed to retain moisture and allow oxygen to pass through, promoting eye health. Polyvinyl chloride (PVC) is primarily used in construction and plumbing products and is not suitable for contact lenses because it is rigid and lacks the necessary biocompatibility and oxygen permeability.

Furthermore, options A) Teflon and C) Perspex (an acrylic polymer) are also unsuitable for contact lenses, as Teflon is primarily known for its non-stick properties in cookware and Perspex is used for clear plastic applications rather than medical uses.

In summary, while none of the given options accurately represent the materials used in contact lens production, the safest choice should be D) "None of them," as contemporary contact lenses are predominantly made from more suitable materials such as silicone hydrogels.