Which process involving dna creates a dna pattern or “fingerprint” unique to an individual person

I think the process is gel electrophoresis. Gel electrophoresis is a laboratory method used to separate mixtures of DNA, RNA, or proteins according to molecular size. In gel electrophoresis, the molecules to be separated are pushed by an electrical field through a gel that contains small pores. The process creates a DNA pattern that is unique to an individual person as it separates DNA, RNA and proteins, DNA fragments are separated according to their size. 

option a is correct i.e.

only sodium ions can pass through the membrane.

explanation:

in context to the membrane of nerve impulse, the outer membrane of neuron is semi permeable that is only sodium ions can pass through the membrane i.e. smaller ions can pass through the membrane while larger ions cannot pass through it.