This disease constitutes a health problem of great importance in much of the tropical and subtropical countries. The Centers for Disease Control and Prevention in the United States estimates that 300 to 500 million cases of malaria occur each year. More than 1 million people die from this disease. Malaria is a much higher disease risk for travelers in hot climates, for example, in the United States, about 1500 cases of malaria are diagnosed each year. The vast majority of cases correspond to travelers and immigrants returning from places in the world where there is malaria transmission, such as Africa and South Asia. Because this disease causes so many cases of illness and death, malaria causes great losses to the difficulties of many countries. Because many countries with malaria are among the poorest nations, the disease maintains a vicious cycle of poverty and disease.
d. Some magma generated during seafloor spreading spills out to produce a new layer of seafloor called gabbro.
Explanation:
The magma is spilled from the mid-oceanic ridges and spreads onto the seafloor creating a newer seafloor.
This is why it's called as the divergent boundary due to the spreading of magma on both sides of the floor. Grabbo is a coarse-grained mafic intrusive igneous rock and is formed at the oceanic ridges.