Which of these units represents a billion bits?

The correct answer is Gigabit.

A gigabit is a unit of digital information that equals one billion bits (1,000,000,000 bits). This unit is commonly used in networking and telecommunications to measure data transfer rates, storage capacities, and bandwidth. In contrast, a kilobit represents one thousand bits (1,000 bits), a megabit corresponds to one million bits (1,000,000 bits), and a terabit is one trillion bits (1,000,000,000,000 bits). Understanding these distinctions is crucial for working effectively with data rates and networking metrics, as it helps in assessing performance and capacity requirements in various network designs.