Answer:
At an occluded front, the cold air mass from the cold front meets the cool air that was ahead of the warm front. The warm air rises as these air masses come together. ... The temperature may warm or cool. After the front passes, the sky is usually clearer and the air is drier.
link: https://www.windows2universe.org/earth/Atmosphere/tstorm/occl_front.html
B is the correct answer to your question hope it helped
Natural selection act directly upon <u>Alleles</u>
Explanation:
Genes, such as that of fur color, have many variants called alleles. Natural selection act on the alleles and chooses the best fit for an environment and eliminates the disadvantageous ones from the population over generations. Mutations are a rare occurrence that increases the number of allelic variants of a genes on which natural selection can act upon.
Khi bạn quỳ lâu, đứng lâu sẽ gây ép lên các cơ bắp và mạch máu. Hoặc một tình trạng khác là khi ngủ bạn thường xuyên để cong chân, cơ bắp ở bắp chân khá ngắn, không được duỗi ra, duy trì tư thế này lâu, khi cử động nhẹ bạn sẽ bị chuột rút.
D. Enzymes and antibodies
