What is the best meaning for the word alternate?
she figured out an alternate path.
a. blocking the way.
b. happening every other time.
c. used instead of something else.
d. longer than usual

The answer is C.
To alternate is to change between different things, so if I were to alternate between two different chairs, I'd be changing between which chair I was using.

In this case, used instead of something else is the best option. That would mean that she figured out a path different to the one that she used to use, hence an alternate one.

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.