Answer:
B modern society
Explanation:
If we still lived in the Dark Ages, we'd all be so busy farming and fighting for survival that there would be no space for leisure goods like contact lenses or developing technology like cell phones. Our modern society enables us to have job specialization: not everyone has to farm. Some people can take time to invent contact lenses. Some people can make those contact lenses.
Why not A: scientific discoveries didn't really impact rock concerts, unless you count the speaker systems. That's too loose.
Why not C: factories produce those items, but they don't directly influence their generation.
Why not D: political change has nothing to do with these items.
