The correct answer is letter (<span>C) The polar air mass moves south to replace the rising maritime tropical air mass.</span> These air masses are bringing cold air to warmer areas most especially during the winter and cool. These air masses are stable and usually does not form much cloud. While the Continental Polar air move down south, across the warmer land, the lower part of the air mass is modified and thus few clouds are formed.
Answer:
Coal is a fossil fuel. It comes from the remains of plants that died about 100 to 400 million years ago. Coal is a non-renewable energy source because it takes millions of years to form
Flu vaccines need to be revised and changed every year because the flu virus constantly mutates. Flu viruses can change in two ways: drift or shift. Antigenic drift occurs when genes of the virus slowly change during replication until the immune system no longer recognizes it. On the other hand, antigenic shift occurs when a major change in the virus happens. This usually leads to a totally different kind of virus. This is what happened during the H1N1 scare in 2009.
DNA viruses like mumps are less prone to mutation due to the presence of DNA polymerase. RNA viruses are more prone to mutation because they undergo reverse transcription to simulate the role of DNA.
