An elliptical sentence is a sentence where some words are omitted because they are understood from the context.
Looking at the options provided:
1. "I travel east and then travel west" - This is a complete sentence without any omitted words, so it is not elliptical.
2. "OI travel east. Marc travels west" - This is also not elliptical as both complete sentences are presented separately.
3. "OI travel east and Marc goes west" - This sentence is structured as two independent clauses connected by "and," so it is not elliptical.
4. "I travel east; Marc, west" - This sentence is elliptical because the verb "goes" is understood to be after "Marc." The sentence could be expanded to "I travel east; Marc goes west."
Therefore, the elliptical sentence among the options is:
4. "I travel east; Marc, west."
