The answer is the first choice:
Negative feedback reverses a change in a variable that has moved outside of its normal range, whereas positive feedback strengthens it.
Feedback loops do not only apply to blood pressure. There are many examples from body temperature regulation to child birth to your AC unit at home.
They are both known to be heavy, hydrogen is one of the two stable isotopes of deuterium
1. During DNA elongation, polymerase enzyme adds new, free nucleotides to the three prime end of the newly forming strand, elongating it in five prime to three prime direction while the telomerase protects the important genes at the end of the chromosome from been deleted as the DNA strand shorten during DNA elongation.
2. During DNA elongation, helicase enzyme separates the double stranded DNA into single strand by melting the hydrogen bond that holds the DNA molecule together thus enabling each strand to be copied while the telomerase acts by preventing the telomere from been deleted during elongation.
They protect bacterial cells from white blood cells.