I believe C is the answer, may be wrong though.
The cardiac cycle is the performance of the human heart from the ending of one heartbeat to the beginning of the next heartbeat.It consists of two periods: one during which the heart muscle relaxes and refills with blood, called diastole, following a period of robust contraction and pumping of blood, dubbed systole.
Scientific ocean exploration began in the 19th century, using wooden sailing ships. At that time, explorers had none of the technological sophistication and tools available today. A comparison of modern-day exploration with the late 19-century journey of the HMS Challenger<span>illustrates the progress that science has made in ocean exploration.</span>
Many could actually occur-
mountains or islands though are the main!
The correct answer is B. Lava flows, pyroclasts.
Explanation
A volcano is a mountain or hill that has an opening through which gaseous, liquid or solid materials can escape from the interior of the Earth. At the top of this cone, there is a concave formation called crater or chimney. When activity occurs in a volcano it is because it is erupting. Also, when it is erupting, the molten rock that comes from the Earth's mantle, known as magma, comes out. Once the magma comes to the surface, it loses the gases it contains because it evaporates, and when it drains the slopes of the cone it is known as lava, which flows from the top of the volcano. Finally, the waste expelled by a volcano through its crater during an eruption is known as pyroclasts. So, the correct answer is B. Lava flows, pyroclasts.
