155. A section of the river that is narrower than usual and is often navigable from bank to bank is a __________.

A chute is the correct answer; it specifically describes a narrow, deep river channel, often navigable from bank to bank, common on U.S. inland rivers. Sloughs are marshy backwaters, stabilized channels are engineered river sections, and navigable passes are dam structures, none of which fit the question's description of a naturally narrow, navigable channel.