Answer:
the answer should be b ot ccc

your answer is given below..
The environment is rich in infectious agents that transmit disease through pathogens.
Answer:
The two strands of DNA need to be separated so new bases can pair with each template strand. What is the significance of the sequence of nucleotides? It determines the type of protein being produced.
I'm not 100% sure, but I think that the digestive system excretes solid wastes only and the excretory system excretes liquid wastes only. So the 3rd option is probably correct.