B. Because there’s a variety of large animals but only sometimes
Answer:
Cell
A virus can only multiply when it is in a cell. It cannot reproduce anywhere else.
Urea enter the kidneys, passes through the ureters and then enters the urethra.
Cell theory was eventually formulated in 1839. This is usually credited to Matthias Schleiden and Theodor Schwann. However, many other scientists like Rudolf Virchow contributed to the theory.