A felsic extrusive igneous rock is formed from

silica-rich lava at Earth’s surface

basaltic lava at Earth’s surface

silica-rich magma within the Earth

basaltic magma within the Earth

Why is the huronian supergroup rock formation particularly interesting to scientists? because it looks like a cross-section of a giant, stone encyclopedia because it formed during the period when oxygen began to accumulate in the atmosphere because it contains unusually large amounts of oxygen and sulfur because it dramatically altered the planet's development when it first formed