Explanation:

- Option 1: Magnetic drum

Magnetic drums were indeed used in first-generation computers. They served as a primary memory device, storing data and instructions.

- Option 2: Hard disk

Hard disks emerged later, around the mid-20th century. They were not used until second-generation computers.

- Option 3: Floppy

Floppy disks came much later, starting in the 1970s. They were not part of the first-generation computer storage solutions.

- Option 4: Both a and c

This option is incorrect because while a magnetic drum was used, floppy disks were not available at that time.

Correct Answer:

- Option 1: Magnetic drum