The photograph of Hunter and his game helps the reader understand that the game — involves a detailed setup
requires a specific number of players
leads to thought-provoking discussions
includes a great amount of physical activity

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.