What situation below is subjunctive? We should go to the lake if we don't have to do chores.
We'll go to the lake after chores.
When we get to the lake, let's swim to the island.
If we go to the lake, we have to hurry through our chores.

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.