The duration of a contraction is best represented by which colored arrow?

Comprehensive and Detailed Explanation From NCC-Aligned Sources:

Contraction duration is defined as the length of time from the beginning of a contraction to the end of the same contraction (NICHD uterine activity definitions).

In the diagram:

Green arrow (B) spans one individual contraction from rise → peak → return to baseline.

Blue arrow (A) measures the interval between contractions (frequency).

Red arrow (C) measures peak-to-peak amplitude shape, not duration.

Therefore, the green arrow correctly identifies contraction duration.