The source-bank answer is B, reflecting the simplified national-exam distinction that owners beside navigable waterways generally own to the water ' s edge, whereas certain nonnavigable-stream ownership questions use the midpoint or thread of the stream.
However, that rule must not be treated as an absolute Massachusetts title rule. Massachusetts waterfront boundaries depend on whether waters are tidal or non-tidal, the deed, historical grants, registered-land records, surveys, public-trust rights, and other legal factors.
Massachusetts Land Court survey guidance expressly recognizes several potentially relevant water boundaries, including mean high water, low water, middle lines, channel lines, and other title-defined boundaries. Massachusetts Chapter 91 also protects public rights in tidelands and qualifying navigable rivers and streams.
Therefore B is the intended licensing-textbook answer, but an actual Charles River parcel boundary cannot responsibly be determined merely from the fact that people canoe on the river.
Study Guide Reference: Property Ownership — riparian rights and water boundaries; Massachusetts public-trust principles.
