Flux is a physical quantity that represents the flow of a property per unit area. It is used in various fields such as physics, chemistry, and engineering. The unit of flux depends on the specific property being measured.

Flux can be defined as the amount of a property (such as mass, energy, or electric charge) passing through a given area per unit time. The SI unit of flux is the amount of the property passing through a unit area in a unit time.

Given the options, let's analyze each one to determine the correct unit of flux:

a) Kg*m^-2*s^-1:
- This unit represents kilograms per square meter per second. It can be interpreted as the amount of a property (in this case, mass) passing through a unit area (square meter) in a unit time (second). This is a valid unit for flux and is commonly used in various fields.

b) Kg*m^2*s^-1:
- This unit represents kilograms times square meter per second. It does not represent flux because it does not involve division by a unit area. It is not a valid unit for flux.

c) Kg*m^2*s^1:
- This unit represents kilograms times square meter times second. It does not represent flux because it does not involve division by a unit time. It is not a valid unit for flux.

d) Kg*m*s^2:
- This unit represents kilograms times meter times second squared. It does not represent flux because it does not involve division by a unit area or time. It is not a valid unit for flux.

Therefore, the correct unit of flux among the given options is option 'a) Kg*m^-2*s^-1'.