Some types of algae live inside coral. The algae provide the coral with nutrients. The coral provides the algae with shelter. Which of the following relationships exist between the algae and coral?
A.
a parasite-host relationship
B.
a symbiotic relationship
C.
a predator-prey relationship
D.
a competitive relationship

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.