Multirate DSP

A: Governing principle: multirate verification starts at the highest rate where aliasing can still be excited. Here, alias energy is created before decimation, so stimulus and observation have to straddle that boundary before any baseband checks mean anything. Option D traps people who know aliasing matters but forget that low-rate excitation can't excite folded spectra.

A: Governing principle: anti-imaging defines what spectra are allowed to survive interpolation. If it leaks, out-of-band energy can fold into the band the safeguard is watching, creating false negatives even though the monitor is 'alive'. Option D catches engineers who conflate phase with imaging, but group delay mismatch is a different safeguard gap.

A: Governing principle: freedom from interference is about unintended coupling paths. A multirate change can move energy and load into places other safety elements didn't anticipate, even if the math still 'works'. Option B tempts people who overgeneralize ASIL rules without checking the actual interference mechanism.

A: Governing principle: rational resamplers assume stable clock ratios. Thermal and aging-induced drift accumulates phase error over time, so issues appear only after long operation, not short bench runs. Option D explains glitches but not the mileage-correlated onset.