Dean is conducting a science experiment. He wants to see how the average length of an earthworm changes with its age. What unit of measurement would be best for Dean to use to measure the lengths of the earthworms in his study?
A.
meter
B.
centimeter
C.
milliliter
D.
liter

its first and third is your answer i did the qustion the fourth isnt right

considering the question as per the attachment

here we can see that the radon nuclide has 222 as the atomic mass number and 86 as the atomic number.

when it undergoes nuclear fission it gives polonium which has atomic mass number as 218 and atomic number will be 84 along with a helium nucleus which has 4 atomic mass number and 2 as its atomic number.

222 = 218 + 4 (atomic mass number)

86 = ? + 2; therefore ? = 86-2 = 84.

the atomic mass number of polonium will be 84.