Drafting equipment and tables: Both the drafting machine and the parallel straightedge (parallel rule) are mounted on specially designed drafting tables to help drafters produce accurate technical drawings.

Introduction / Context:
This question targets foundational knowledge of traditional drafting hardware. Before widespread CAD adoption, precision mechanical aids—drafting machines and parallel straightedges—were integral to producing accurate lines and angles.

Given Data / Assumptions:

• A drafting machine combines a protractor head with rulers, sliding on tracks attached to the board.
• A parallel straightedge rides on cables or tracks to keep the edge perfectly parallel as it moves.
• Both devices are intended for use on rigid, purpose-built drafting tables or boards.

Concept / Approach:
Accuracy in manual drafting relies on stable reference edges and repeatable geometry. The drafting table provides a flat, stable, and square surface. The machine or straightedge ensures repeatable parallelism and precise angle setting, minimizing human error and cumulative inaccuracies.

Step-by-Step Solution:
Recognize the function of a drafting machine: quick setup of common angles and parallel lines using linked rulers.Recognize the function of a parallel straightedge: maintain a constant reference edge across the sheet.Note that both are installed on dedicated boards/tables for rigidity and calibration.Conclude the statement correctly describes their intended use.

Verification / Alternative check:
Standard drafting texts and lab setups show these devices permanently mounted to drafting boards, not freestanding or handheld.

Why Other Options Are Wrong:
“Incorrect” ignores the basic design of the tools. Limiting to architecture or to a pre-1950 era is historically inaccurate; engineers and designers across disciplines used them for decades. Paper type (vellum, film) is secondary to the mechanism.

Common Pitfalls:
Confusing a T-square (handheld against the board’s edge) with a parallel straightedge (cable-mounted). Both need a proper drafting surface.

Final Answer:
Correct