BCD counter is also known as Decade counter

A BCD (Binary-Coded Decimal) counter is a type of counter that counts in the binary-coded decimal system. It is commonly used in applications where decimal counting is required, such as in digital clocks, calculators, and electronic counters.

Explanation:

A BCD counter is a synchronous counter that counts in the binary-coded decimal system. It consists of four flip-flops, each representing one decimal digit. The flip-flops are connected in a cascade configuration, with the output of one flip-flop connected to the clock input of the next flip-flop.

Parallel counter: A parallel counter is a type of counter where all the flip-flops change state simultaneously in response to a clock pulse. In a BCD counter, the flip-flops change state in parallel, which allows for efficient counting in the binary-coded decimal system.

Synchronous counter: A synchronous counter is a type of counter where all the flip-flops are clocked by the same clock signal. In a BCD counter, the flip-flops are clocked by the same clock signal, ensuring that they change state at the same time.

VLSI counter: VLSI (Very Large Scale Integration) counter refers to a counter that is implemented using VLSI technology. VLSI counters can be implemented using various technologies, such as CMOS (Complementary Metal-Oxide-Semiconductor) or TTL (Transistor-Transistor Logic). While BCD counters can be implemented using VLSI technology, not all VLSI counters are BCD counters.

Therefore, the correct answer is option B) Decade counter, as a BCD counter is a type of counter that counts in the binary-coded decimal system, representing decimal digits using four flip-flops.