Replication of the nucleus.
        
             
        
        
        
Answer:
I am pretty sure that the answer is A.
Explanation:
Protein kinases regulate the cell cycle by giving the "go-ahead" or "stop" signal at checkpoints in the cycle. A mutation/disruption in the protein kinases can result in it not doing its job properly. As a result, it can give the 'go-ahead' signal to all cells (mutated or not) to continue through the cell cycle. A distrupted kinase will infleunce the enviornment for a cancer cell as the cancer cell can continue to divide continuously. 
I do not think the answer is D because G-couped receptirs are not involed in the regulation of the cell cycle. Additionally, I do not think the answer is C since the production of cAMP (a secondary messgenger amplifies transduction signals; this doesn't have anything to do with cancer?) Finally, between A and B I know that a direct result of cancer is due to a distruption in either protien kinases or  growth factors (not in the answer choices). Since one of the factors that  leads to cancer is present in answer choice A, I think that is the one. However, this is just my reasoning, I am not 100% sure! 
 
        
             
        
        
        
Rolling a die multiple times to see the average.
        
             
        
        
        
The dehydration is a very common problem seen in elderly individuals. At an elderly age, all the body functions are diminished, which lead to reduction in thirst and body's ability to obtain water. That is why, the elderly people are very susceptible to dehydration. 
In order to remain healthy, a person must take 2.5- 4 litres of water per day. In males, the water is required more than females. So, for males, the adequate intake (AI) of water should be in between 3-4 litres per day.