Abacus was the first:

Correct option is D

The Abacus was the world’s first mechanical calculator, developed in ancient times to perform basic arithmetic operations like addition and subtraction. It used beads and rods to represent numbers and carry out calculations manually, without any electricity.

Important Key Points:

1. The Abacus is a manual device used for basic calculations.
2. It represents an early form of computing technology before digital and electronic systems.
3. Widely used in ancient China, Egypt, and Mesopotamia for trade and commerce.

Knowledge Booster:

•       Electronic computer – Refers to machines like ENIAC, developed in the 20th century, not Abacus.

•       Mechanical computer – More advanced than the Abacus, e.g., Charles Babbage's Analytical Engine.

•       Electronic calculator – A modern device using electrical components, not related to the Abacus.