I need help on this question

Volcanic irruption is most likely to be violent when a) volcanoes near to the sea b) the neck of the volcano is sealed by a plug c) the lava is viscous d) the lava reaches the surface through a fissure e) the volcano is on the ocean floor

Which are evidence of the seafloor spreading? a. molten material b. magnetic stripes c. continental material d. drilled core samples e. ocean water samples

Which ecosystem best fits the characteristics listed below? which ecosystem best fits the characteristics listed below? ii. seasonal migrations of millions of wildebeests, zebras, and elephants iii. large numbers of predators, such as lions iv. acacia trees and grasses a. the congo rainforest b. the african mangroves c. the serengeti grasslands d. the sahel