In this example question, it asks which statement about primary nucleic acid structure is incorrect:

• The structure and function of a nucleic acid are based on the sequence of the connected nucleotides. That statement is true.
• The sequence of nitrogenous bases is read from the 5′ to the 3′ end. This statement is also true.
• A phosphodiester bond represents a bond between the phosphate group and the sugar. This is also true.

So, the last one, "The difference between Nucleic Acids is a result of the difference of the sugar attached to the backbone," is incorrect. Remember, the diversity or differences between nucleic acids are primarily based on the differences in their nitrogenous bases, not the backbone. Therefore, statement D is the incorrect statement out of all the options given.