Which mathematical product design innovation first introduced dynamic visualization of equations, allowing users to manipulate variables and instantly see graphical changes?

Throughout history, mathematical tools and products have evolved dramatically to help solve increasingly complex problems. From ancient calculating devices to modern computational tools, mathematics product design has been shaped by both technological innovation and educational needs. This trivia question explores a significant milestone in the development of mathematical learning products that revolutionized how people interact with mathematical concepts.

This is a live public trivia poll on AIPolls.Net. Vote and see real-time results.

The ENIAC computer (1945)
Graphing calculators with CAS (Computer Algebra Systems) in the 1990s
The slide rule's logarithmic scales (17th century)
Microsoft Excel's first formula functions (1985)