Which of the following ensures that a crystal oscillator operates on the frequency specified by the crystal manufacturer?

Quartz crystals used in electronic oscillators are cut and calibrated to resonate at a specific frequency, but their exact resonant frequency in a real-world circuit depends on the electrical load they are connected to. Manufacturers specify a "load capacitance" (a specific parallel capacitance) that must be present across the crystal's terminals for it to oscillate exactly at its marked nameplate frequency. If the parallel capacitance in the circuit is higher or lower than the manufacturer's specification, the crystal's frequency will be "pulled" slightly off target. Biasing voltages, currents, or parallel inductances are not the standard parameters used to align a standard quartz crystal to its specified operating frequency.