Computer Science for IGCSE & O level - Hardware (Section 11 - No. 38)
What are the essential parts of a barcode?
1 to 6 wide blocks and two lines.
2 dark lines and 2 light lines.
2 dark lines and 1 light line.
2 dark lines and 3 light lines.
Explication
The text says that two dark lines and two light lines make up a barcode.