Final answer:
A Quality Control (QC) program tests for beam alignment, reproducibility, and linearity to ensure equipment and processes operate correctly, making all three aspects important.
Step-by-step explanation:
The question is concerned with components of a Quality Control (QC) program in a technical or scientific setting. Quality control is vital to ensure that equipment or processes are functioning correctly and producing reliable results. The QC program typically includes testing for beam alignment, which ensures that any beams used are accurately targeted; reproducibility, which checks if repeated measurements under unchanged conditions are consistent; and linearity, which confirms that the output signal changes proportionally with the input signal. Therefore, all three aspects you mentioned - beam alignment (1), reproducibility (2), and linearity (3) - are tested in a QC program.