Gold standard of prosthetic replacement is:: (A) Duplicate in the replacement to natural, (B) Comfortable & stable in function, (C) Socially acceptable in aesthetics, (D) These should be maintained throughout their serviceable lifetime at a reasonable cost
Answer is A. Tooth replacement prosthesis properties:

Duplicate in the replacement to natural (Gold standard)
Appearance (socailly acceptable)
Function (comfortable & stable)
Maintenance (throughout their serviceable lifetime on reasonable cost)