Meter gives poetry a predictable rhythm and influences how a poem is read, both silently and aloud. what is the basic unit of meter in poetry? a foot a trochee an unstressed syllable an iamb

The basic unit of meter in poetry is a foot.
Syllable would be the correct answer if the option said 'stressed or unstressed syllable,' because there are two types of syllables, not only the unstressed one. An iamb and a trochee are types of feet in poetry, so they are incorrect as well. A foot is a unit of meter which consists of a number of syllables. 

The best answer in my opinion would be the last one. i hope this