What is a logical fallacy?

a mistake in thinking or reasoning
a system of thought analysis
a true or false statement
a process of reaching conclusions

The Answer is C! 

A mistake in thinking or reasoning. 

Okay, biology isn't exactly my strongest subject (it never has been), but i'm pretty sure the answer is nucleotides. dna is made up of nucleotides. each nucleotide contains a phosphate group, a sugar group, and a nitrogen base. there are four different nitrogen bases: adenine (a), thymine (t), guanine (g), and cytosine (c). a always pairs with t, and g always pairs with c.