Final answer:
C. All cells contain the same copy of DNA is the correct statement; this enables different genes to be activated in specialized cells for unique protein formation, defining each cell's function through a process known as differentiation.
Step-by-step explanation:
The statement that correctly describes the DNA in all body cells in a human is that C. All cells contain the same copy of DNA, where different genes are activated to form unique proteins. This means that although every cell in a human body contains the same set of DNA sequences, they do not all express the same genes. Specialized cells such as those in the liver or eyes only produce a subset of proteins that are relevant to their particular function by selectively activating certain genes within their common genome. The process in which cells with the same DNA become different types of specialized cells through the expression of different genes is known as differentiation. It is like actors reading from the same movie script but only performing their specific parts. Therefore, cells become specialized and distinct from one another not by containing different types of DNA but through a highly regulated process of gene expression that is meticulously controlled for precision and specificity.