Logic-level naming in positive logic: In a standard positive-logic system, the lower valid input voltage region is termed the ________ level.

Introduction / Context:
Digital logic specifications define valid voltage regions for interpreting binary states. In positive logic, conventions label the higher voltage region as logic 1 (HIGH) and the lower region as logic 0 (LOW). This question confirms your grasp of that terminology.

Given Data / Assumptions:

• Positive-logic convention is assumed.
• Two non-overlapping valid regions exist, with an undefined region between them.
• We are naming the lower valid region.

Concept / Approach:
By definition, positive logic assigns logic 1 to higher voltages and logic 0 to lower voltages. Therefore, the lower valid region is called the LOW level and represents logic 0. Datasheets specify VIL (maximum low input voltage) and VIH (minimum high input voltage) to guarantee correct recognition.

Step-by-Step Solution:

Verification / Alternative check:
TTL/CMOS families publish input-level tables showing VIL max and VIH min; the lower region is consistently labeled LOW.

Why Other Options Are Wrong:
HIGH: refers to the upper region.

off: ambiguous; not a standard logic-level name.

unacceptable: describes the undefined region, not a valid level.

Common Pitfalls:
Confusing output voltage levels with input threshold specifications; while related, both use the same HIGH/LOW naming for valid regions.

Final Answer:
LOW