In plotting technologies, “resolution” for electrostatic plotters denotes the density of picture elements; it is typically specified as the number of dots per inch (dpi), unlike pen plotters where resolution is the shortest reliably drawn line.

Introduction / Context:
Plotters render images either by physically drawing with a pen (vector plotters) or by forming images from discrete dots (electrostatic, inkjet, or laser). Understanding how resolution is defined for each technology helps in selecting devices for engineering drawings, cartography, or large-format graphics.

Given Data / Assumptions:

• Pen plotters draw continuous lines with a physical pen.
• Electrostatic plotters form images using charged dots on media.
• Resolution should reflect the smallest detail the device can represent.

Concept / Approach:
For electrostatic plotters (and modern pixel-based devices), resolution is the dot density, commonly measured in dots per inch (dpi). Higher dpi allows finer features and smoother curves approximated by more dots. By contrast, a pen plotter’s “resolution” is often described by the minimum line width and the mechanical precision of stepper movements, not by a dot grid.

Step-by-Step Solution:
Identify technology: electrostatic = raster/pixel formation.Define resolution accordingly: dots per inch along each axis.Confirm that alternatives (speed, tracking accuracy) are performance metrics, not resolution.Select “number of dots per inch” as the correct definition.

Verification / Alternative check:
Device specifications for electrostatic or laser printers list dpi as the primary resolution figure (e.g., 300 dpi, 600 dpi), validating the definition.

Why Other Options Are Wrong:
Speed per inch: measures throughput, not detail.Dual-axis tracking: refers to motion control, not image detail.Return accuracy to a point: a positioning precision metric, not raster resolution.None of the above: incorrect because dpi is correct.

Common Pitfalls:
Confusing mechanical precision (repeatability) with raster resolution; both matter, but only dpi defines the smallest drawable pixel detail for electrostatic devices.

Final Answer:
The number of dots per inch