Final answer:
The subject of this question is English and the grade level is High School. The combined set of observations about the rules governing the formation of morphemes and syntax that guide language use is referred to as the lexicon and grammar of a language.
Step-by-step explanation:
Language, be it spoken, signed, or written, has specific components: a lexicon and grammar. Lexicon refers to the words of a given language. Thus, lexicon is a language's vocabulary. Grammar refers to the set of rules that are used to convey meaning through the use of the lexicon (Fernández & Cairns, 2011). For instance, English grammar dictates that most verbs receive an "-ed" at the end to indicate past tense.