Most people would identify the phrase "red tide" as something to do with threatening the world. It appears with increasing frequency along the sea coasts of many countries, usually as follows: With no warning, a portion of the sea begins to turn a dull shade of red. As the color begins to deepen, strange events take place. Fish leap straight up out of the water and fall back dead. Piles of fish slowly collect on the beaches. Dead and dying fish float belly up on the surface of bays and inlets. Waves glow eerily at night. Eventually all marine life touched by the red tide is destroyed. And not only marine life is harmed. Men suffer too. Fishermen are left without fish to catch, and are thus without a livelihood. Areas which depend on tourism can attract no tourists until millions of stinking Fish are cleared from their shores. The harm to both man and nature is incredible.

Q. Underline the sentence which states that "red tide" is an unfamiliar term.