I can help if you put the options. (A. B. C. D.)
Answer: In 1858, Pasteur filtered air through a gun-cotton filter and, upon microscopic examination of the cotton, found it full of microorganisms.
I hope this helped!
<span>USA: Osteoporosis and low bone mass are currently estimated to be a major public health threat for almost 44 million U.S. women and men aged 50 and older. I hope this is correct.</span>
