1. The correct answer is S-V-N.
S refers to subject, and if you take a look at the sentence, you will see that the subject IT comes first. It is then followed by V, which stands for verb. In this sentence, the verb is IS. The verb is followed by a noun phrase HYBRID CAR, which is a predicate nominative (a noun or phrase following a linking verb). Predicate nominatives are written as N.
2. The correct answer is S-V-A.
The layout of this sentence is similar to the first sentence. First, we have the subject (S) TRADITIONAL GAS-POWERED CARS, then we have the verb (V) ARE, which is later followed by an adjective phrase HARMFUL TO THE ENVIRONMENT. This phrase is a predicate adjective (an adjective or adjectival phrase following a linking verb), which is written as A.
3. The correct answer is S-V-O.
This is the most common structure of sentences in the English language. First, we have the subject HYBRIDS, then we have the verb PRODUCE, and then we have the direct object LESS POLLUTION, and later a phrase that we don't need to name. The object of a sentence is determined by asking the question What? (What do hybrids produce? - Less pollution), and it is written as O. IO stands for indirect object, which doesn't appear here.
