Outline the sequence of lens formation starting from surface ectoderm to the final lens fibers.

• A. Surface ectoderm thickens to form the lens placode; placode invaginates to form the lens vesicle; anterior lens epithelium forms the lens epithelium and secondary lens fibers postnatally; posterior cells of the lens vesicle elongate to form primary lens fibers.
• B. Surface ectoderm thickens to form the lens placode; placode invaginates to form the lens vesicle; posterior cells of the lens vesicle elongate to form primary lens fibers; anterior lens epithelium forms the lens epithelium and secondary lens fibers postnatally.
• C. Surface ectoderm thickens to form the lens placode; placode invaginates to form the lens vesicle; anterior cells elongate to form primary lens fibers; posterior lens epithelium forms the lens epithelium.
• D. Surface ectoderm forms the cornea; lens placode forms; lens vesicle degenerates.

Answer: (B)