Institution: Bangladesh Public Service Commission (BPSC বিসিএস ) Exam: 43th BCS Preliminary Exam 2021
Topic: ICT (তথ্য ও যোগাযোগ প্রযুক্তি), Subject: Computer and ICT (তথ্য ও যোগাযোগ প্রযুক্তি)

Best Answer Explained in Below-:

The correct answer to the question of how data transmission occurs between a keyboard and a CPU is **Simplex (Option A)**. In a simplex communication system, data flows in only one direction. When you press a key on your keyboard, it sends a signal that travels to the CPU, indicating which key was pressed. This communication involves sending data from the keyboard to the CPU with no return signal or data going back from the CPU to the keyboard.

In contrast, duplex communication allows data to be sent in both directions simultaneously. For example, in a full duplex system, devices can communicate back and forth at the same time, similar to a phone conversation. Half duplex allows for two-way communication but not simultaneously; one device sends while the other receives.

Keyboards do not need to receive data back from the CPU after each keystroke, making simplex the most suitable descriptor for this interaction. This one-way data transmission is efficient and adequately meets the needs of the keyboard’s operation with the CPU. Therefore, Simplex accurately represents the communication method between these two devices.