The two differences you see when comparing the four chambers of the heart is that the arteries have a thicker wall and veins have thin walls and that the arteries carry oxygenated blood away from the heart which means they get more pressure than veins.
        
             
        
        
        
The correct sequence is sources emit greenhouse gases; global temperatures rise; snow and ice melt; and sea levels rise. The natural and man made sources emit greenhouse gases that are responsible for the greenhouse effect. The increase in the Earth's temperature due to these gases absorbing more heat from the sun caused climate change like melting of snow and ice which contributes to the rising sea levels.
        
             
        
        
        
Answer:

Explanation:
We recognize that total occurrence equals new cases of disease over time divided by the number of people at risk at the onset.
Mathematically:

Given that:
Number of the population at risk = 1000 individuals
New cases during Jan 1 - Dec 31 = 60 because;
At 20 occurred on June 30 & 40 on Sept. 30) & no new cases were identified after that:
∴
