When the goal is to compare two signals simultaneously (for example, input versus output of an amplifier) and see timing and amplitude relationships on the same screen, which piece of test equipment makes this task easiest?

Introduction:
Visual comparison of two waveforms is central to debugging amplifiers, filters, and digital interfaces. The right tool should display both signals with a common time base so that relative phase, delay, gain, and distortion are immediately visible.

Given Data / Assumptions:

• Two signals need to be observed at once.
• We care about amplitude and time alignment.
• Real-time visualization is preferred.

Concept / Approach:
A dual trace (two-channel) oscilloscope shows both signals on the same screen with a synchronized horizontal sweep. You can overlay or stack channels, measure time differences, and quantify gains/offsets. Other instruments either cannot show two time-domain traces together or do not provide time correlation directly.

Step-by-Step Solution:
1) Determine requirement: simultaneous, time-correlated display of two signals.2) Match instrument capability: two-channel scope provides exactly that.3) Confirm ancillary features: cursors, math, and triggering further aid comparison.4) Choose dual trace oscilloscope as the most straightforward option.

Verification / Alternative check:
Modern DSOs (digital storage oscilloscopes) with two channels are standard in labs for exactly this purpose; engineers routinely compare input and output or two nodes in a circuit.

Why Other Options Are Wrong:
Spectrum analyzer: frequency-domain instrument; not suited to time-domain comparison.Multimeter: single scalar readings; no waveforms.Function generator: produces signals; does not display two signals for comparison.

Common Pitfalls:
Trying to infer timing relationships from separate single-channel captures; simultaneity is critical for accurate comparison.

Final Answer:
dual trace oscilloscope