Step 1: What is calibration?
Calibration is the process of comparing the readings of an instrument against a known standard and adjusting the instrument so that its readings are correct. It is a fundamental quality control step in any analytical laboratory.
Step 2: Evaluate the wrong options.
High sensitivity (Option 1) is a property of the analytical method, not something calibration directly ensures. Faster analysis (Option 3) is unrelated to calibration. Less reagent use (Option 4) is also unrelated; calibration does not change reagent consumption.
Step 3: Why does calibration ensure accuracy?
An instrument can drift over time, or give a biased reading due to wear, environment changes, or operator handling. Calibration corrects these errors by aligning the instrument's output to a certified standard. After calibration, you can trust that the reading you get is the true value of what you are measuring.
Step 4: Confirm Option 2.
The primary and direct purpose of calibration is to ensure that an instrument gives accurate readings. Every pharmacopoeial method requires instruments to be calibrated before use.
Step 5: Quick summary.
Calibration = accuracy check and correction of instrument readings.
Answer: Option (2) — Accuracy of instrument readings