Paul's family is moving across town, so his father rented a moving truck for the day. A ramp pulls out of the truck bed. The bed of the truck is 1 m high, and the
ramp is 3 m long.

i think it's c. i'm not sure but i think so.

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.