Digital logic concept check — structure of a NAND gate: Evaluate the statement: “A NAND gate is constructed by connecting an AND gate and an OR gate in series.” State whether this is accurate in standard Boolean logic hardware.

Introduction / Context:
NAND is one of the four fundamental logic operations used to build digital systems. Understanding how a NAND gate relates to basic operations like AND, OR, and NOT helps students correctly interpret truth tables, simplify expressions, and analyze gate-level schematics. The prompt tests whether a learner knows the functional composition that defines a NAND gate.

Given Data / Assumptions:

• The claim is that a NAND gate equals an AND gate placed in series with an OR gate.
• We assume two-input gates, positive logic, and standard Boolean behavior.
• “Connected in series” is interpreted as cascading the output of one gate into the input of another.

Concept / Approach:
By definition, NAND is the logical complement of AND. Symbolically, NAND(A,B) = NOT(AND(A,B)). This means the canonical construction is an AND gate followed by a NOT (inverter). There is no OR operation in the basic definition. Using OR would change the truth table and produce a different function altogether (e.g., an AND followed by OR with some other signal is not a NAND).

Step-by-Step Solution:

Verification / Alternative check:
Truth table check: AND(1,1)=1, all else 0. NAND is the opposite: outputs 0 only when both inputs are 1. Cascading an AND into an inverter reproduces that exactly; inserting an OR cannot produce this behavior without extra inputs or inversion.

Why Other Options Are Wrong:

• Correct: Conflicts with the formal definition of NAND.
• Wired-logic TTL / CMOS pass-transistor logic / delay dependent: Implementation style or timing does not redefine the Boolean function.

Common Pitfalls:
Confusing the structural implementation (transistor networks) with the functional composition; forgetting that NAND = AND + NOT, nor AND + OR.

Final Answer:
Incorrect