MSI logic concept — multiplexer behavior: In medium-scale integration (MSI) digital design, a multiplexer (MUX) is a data selector that routes exactly one of several input lines to a single output line under the control of select signals. Evaluate the statement: “A device that selects one of several inputs to be placed on the output is a multiplexer.”

Introduction / Context:
A multiplexer (often abbreviated as MUX) is one of the most widely used MSI building blocks. It appears in datapaths, bus interconnects, arithmetic logic units, and test access paths. The defining purpose of a MUX is selection: many inputs, one output, with select lines choosing which input is forwarded. This question checks your understanding of that core definition and distinguishes it from related components such as demultiplexers, encoders, and bus transceivers.

Given Data / Assumptions:

• A device has multiple data inputs (e.g., D0…D7).
• It provides a single data output (Y).
• Control (select) inputs (e.g., S2 S1 S0) choose which Di connects to Y.
• Enable pin, if present, gates the function on or off.

Concept / Approach:
By definition, a multiplexer performs one-of-N selection. For a 2^n-to-1 MUX, there are n select lines. Internally, logic gates steer exactly one input to the output. The function can be viewed as a truth table where Y equals Di when S encodes i. This is distinct from a demultiplexer (1-to-N), which routes one input to exactly one of several outputs, and from encoders/decoders, which transform between one-hot and binary codes.

Step-by-Step Solution:
Identify the direction: many inputs → one output, controlled by selects = multiplexer.Confirm that only one input is active at the output for any select combination.Note that enabling disables or permits the selection without changing the definition.Therefore, the statement matches the formal definition of a MUX.

Verification / Alternative check:
Datasheets for 74xx151 (8-to-1) or 74xx157 (quad 2-to-1) describe “data selector/multiplexer,” confirming this exact behavior. Textbooks likewise define MUX as one-of-N selection.

Why Other Options Are Wrong:
“Incorrect” denies the standard definition. The options invoking demultiplexers or tri-state bus drivers describe different components: DEMUX routes one input to many outputs; bus drivers buffer or isolate lines but do not inherently select among many inputs.

Common Pitfalls:
Confusing MUX with serializer hardware; serialization requires timing and switching over time, whereas a basic MUX is an instantaneous selector governed by static select inputs.

Final Answer:
Correct