Answer:
A.) a proton and an electron
KE = 1/2 mv^2
KE = 1/2 (700)(80)^2
KE = 2240000 J
(any unit of mass) x (any unit of speed) is a unit of momentum.
The only choice on the list with the dimensions of (mass) x (speed)
is 'c'.
'a' is a unit of force.
'b' is meaningless.
'c' is a false statement.