Does anyone know a better introduction i can use for this?

If this is for Percy Jackson and the Lighting Thief chapter 19, "We Find Out the Truth, Sort of," when they are in Hades thrown room then this scene shows that the friends are willing to sacrifice for each other for the happiness and safety of the others. This also shows the trust that the friends have for one another. Percy had been accused of taking the master bolt, and when it was found in his backpack, both Annabeth and Grover knew and trusted Percy enough to know that he had not taken it. Towards the end of the chapter Percy leaves his mom behind in the underworld with Hades. Both Annabeth and Grover try to persuade Percy to let them stay in the underworld so Percy can have his mom, but Percy declines and takes Annabeth and Grover with him back to the surface.

Iwould say you should mainly cover the areas about how it has no health issues or concerns, and also cover the cost, and benefits.

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.