The answer is C.
Hershey and Chase did an experiment to determine whether it was the protein or the DNA that was the transformation principle in viruses by infecting bacteria cells with a virus.
They tagged the protein shell and the DNA and introduced them into a culture of bacteria cells. They concluded that it was DNA that entered the bacteria cells and not the protein.
Again the answer is C.
Chromosomes are tightly wound strands of DNA.
I would go for (4) because I know that it would reject it therefore it would attack the organ since it's a foreign object to the body.
The Answer is D Decomposers. Hope this helps!