Which statement gives the safest summary?

Cause of Ghayr Munsarif: Sighat Muntaha al-Jumu'

• Every plural is ghayr munsarif.
• Only meaning determines declension.
• The taught صيغة منتهى الجموع form stands for two causes; other broken plurals may remain declinable, and the form can also govern certain singular lexical items.
• ال never changes the genitive ending.