What four nitrogenous bases make up the "ladder rungs" of the DNA double helix?

The correct answer identifies the four nitrogenous bases that serve as the fundamental building blocks of DNA. In the structure of DNA, these bases—adenine, guanine, thymine, and cytosine—pair with one another to form the "rungs" of the double helical ladder. Specifically, adenine pairs with thymine, while guanine pairs with cytosine.

This pairing is crucial for maintaining the integrity of genetic information, as it ensures that the strands of DNA are complementary to each other. The sequence of these nitrogenous bases encodes the genetic instructions necessary for the development and functioning of all living organisms. By correctly identifying these four bases, one demonstrates an understanding of DNA's structure and its role in heredity and biological processes.

The other provided options include incorrect or non-existent bases. For instance, tryamine and cortisol are not recognized nitrogenous bases in the context of DNA, and glucose is a sugar that is part of the nucleotides but not a base itself. Thus, option A is the only choice that accurately lists the nitrogenous bases found in DNA.