Which sentence uses dashes correctly? When the man found out the truth—he was upset—and walked away.

After discovering the errors in her writing—all nine of them—she corrected her work.

The dog chased the squirrel all the way—down the block.

The students went on the field trip the next day and—had a great time.

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.