Apparatus calibrated for fixed volume measurement

Steps:

• Identify common volume-measuring tools: beakers (approximate), graduated cylinders (variable levels), pipettes/volumetric flasks (fixed mark), burettes (variable drainage).
• Note that "always filled to the same level" implies a tool designed for precise, consistent filling to a calibration mark.
• Eliminate tools allowing variable filling for different volumes.
• Select the tool requiring filling to a single etched line for accurate, repeatable volume.

Why C is correct:

• A pipette or volumetric flask is calibrated to deliver or contain an exact volume when filled precisely to its single mark, per standard laboratory definition for fixed-volume apparatus.

Why the others are wrong:

• A: Beaker has no calibration marks, so filling level varies by approximation.
• B: Graduated cylinder uses multiple marks for variable volumes, not a fixed level.
• D: Burette fills to top but drains to varying levels for titration volumes.

Final answer: C