It is not c or d. I think it is a.
Answer:
Advantages of written communication: Easy to preserve: The documents of written communication are easy to preserve. Oral and non-verbal communication cannot be preserved. If it is needed, important information can be collected from the preserved documents.
Answer:
<u><em>They take nutrients needed by healthy cells, and as they grow they interfere with the function of normal cells and organs.</em></u>
Explanation:
Many mutations can lead to the formation of cancer. Cancer can be described as an abnormal type of cell division of the cells of the body. As cancer cells are the cells of the body dividing abnormally, the immune cells fail to fight them. These cells keep on dividing and also disturb the functioning of the neighbouring cells and tissues. They even take up most of the nutrients required by normal body cells hence, being very toxic for the normal cells.