Which of the following scenarios best describes the activity present along the mid-atlantic ridge? magma is created by partial melting of crustal material as it sinks. magma wells up at the center of the ridge, which pushes the old seafloor apart as new seafloor is created. a plume of hot mantle material is pushing up against the crust, adding material to the crust to thicken it. segments of seafloor slide past each other without creating or destroying crustal material. old seafloor is consumed as it is forced beneath another segment of seafloor.

Magma wells up at the center of the ridge, which pushes the old seafloor apart as new seafloor is created

Explanation:

The Mid-Atlantic Ridge is formed at the divergent boundaries of the North American and Eurasian plates, and the South American and African plates. This basically means that these plates are moving away from one another, living thinner, fragile crust behind them. The magma from the mantle manages to penetrate through it relatively easy, and as it reaches the ocean floor it quickly cools off and creates new crust. The magma continuously rises, and it piles up more and more new crust, while in meantime pushing the old crust sideways and moving it further away from center of the ridge from the the ocean spreading occurs.

81 is a composite number.