Answer:
There are five (5) iambs in each line.
Explanation:
Birches by Robert Frost is a single stanza poem of Fifty nine(59) lines published in 1916. It is a blank verse poem because it is unrhymed and in iambic pentameter.
Iambic pentameter is one of the most commonly used meters in English poetry. Iambic pentameter means each lines contains five (5) iambs. An iamb being one unstressed syllable followed by one stressed.
When I / see BIR / ches BEND / to LEFT / and RIGHT