The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary (K–T) extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago.
I believe the answer is A
Answer:

Explanation:
Hello,
In this case, the pH is computed by:
![pH=-log([H^+])](https://tex.z-dn.net/?f=pH%3D-log%28%5BH%5E%2B%5D%29)
Whereas the concentration of hydrogen ions equals the concentration of the acid for strong acids such as hydrochloric acid (HCl) due to its complete ionization in solution, which means that such concentration is 0.00125 M. Thus, the pH turns out:

Regards.
Answer:
You should say NO in a firm voice because they will know that you are positive in your decision and hopefully they will leave you alone. If they don't then that is when you start taking other steps in order to avoid peer pressure. I hope this helps!
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4) stimulating the production of antibodies
so in future when you catch the same cold your body will be able to produce antibodies quickly because the memory cell remembers the antibodies that fights off the colds
i hope this helps and sorry if this is wrong