I want to know the answer to the following question:
What is an important plural alternation?
All the background I'm provided with is that "The most important one is the addition of -o- before certain consonant groups, a phonetic phenomenon that does not affect feminine forms: el pols/els polsos ("the pulse"/"the pulses") vs. la pols/les pols ("the dust"/"the dusts").". Is that enough to answer the question?