Final answer:
The rule not associated with syntax is number 3, which is a pronunciation rule. Syntax is related to the structure of sentences, not the pronunciation of words. Subject/verb agreement and noun phrases as subject complements are examples of syntactical rules.
Step-by-step explanation:
The rule of syntax that is not an example is: 3) To pronounce the plural of a regular noun, say the noun and add "S" if the noun ends in a hard consonant and add "Z" if the noun ends in a soft consonant or vowel. This rule pertains to pronunciation rather than syntax, as syntax is concerned with the arrangement of words and phrases to create well-formed sentences in a language.
Subject/verb agreement is an important rule of syntax; for example, the sentence "The play with such true witticisms and parables comes highly recommended." correctly identifies "play" as the singular subject, so the singular verb "comes" is used. Similarly, noun phrases that act as subject complements, as in the sentence "It sounds like a good idea!", demonstrate the syntactic rule that subject complements often follow a linking verb and describe or complete the subject.