I'm for certain the answer is a.) b<span>oth viruses and bacteria are invisible to the naked eye.
</span>
Answer : The molar concentration is, 
Explanation :
First we have to calculate the moles of protein.

Number of molecules of protein = 2 molecules
Avogadro's number = 

Now we have to calculate the radius.
Radius = 
Conversion used : (1 mm = 0.001 m)
Now we have to calculate the volume.



Conversion used : (1 m³ = 1000 L)
Now we have to calculate the molar concentration.



Thus, the molar concentration is, 
<h2>
<u>MILKY WAY GALAXY</u></h2>
The Milky Way galaxy is our home galaxy. It is a kind of spiral galaxy where solar system, including the Sun, the planets, asteoroids, comets along with billions of small celestial bodies are found.
<h2>
<u>WHAT IS THE CENTER OF MILKY WAY? </u></h2>
~ The center of Milky Way galaxy is a supermassive black hole known as Sagittarius A*. This black hole was discovered in 1974 by Bruce Balick and Robert L. Brown.
Sagittarius A* can be seen in the night sky using radio telescopes within the constellation Sagittarius - a constellation discovered by Ptolemy. This black hole is so massive that it's literally equivalent to more than four million suns compressed altogether.
In an atom, the nucleus is composed of protons and neutrons, while the electrons orbit very quickly around the nucleus.
Answer:
The Earth might seem like it has abundant water, but in fact less than 1 percent is available for human use. The rest is either salt water found in oceans, fresh water frozen in the polar ice caps, or too inaccessible for practical usage. While population and demand on freshwater resources are increasing, supply will always remain constant. And although it's true that the water cycle continuously returns water to Earth, it is not always returned to the same place, or in the same quantity and quality.