Fluorine has an atomic number of 9. the n = 1 energy level has two electrons, and the n = 2 energy level has seven electrons. flourine's valence is

+2
-2
+1
-1

c.) polymerase chain reaction

- "unlike the original dna fingerprinting method, dna profiling does not use restriction enzymes to cut the dna. instead it uses the polymerase chain reaction (pcr)? to produce many copies of specific str sequences. pcr is an automated procedure that generates lots of copies of a specific sequence of dna."

i believe your answer would be c.. : )

answer australia and antarctica;