To solve the question regarding the relationship between mass and weight, let's understand the fundamental definitions and principles:

1. Mass:
   • Mass is a measure of the amount of matter in an object.
   • It is measured in kilograms (kg) in the SI system.
   • Mass is a scalar quantity and is constant regardless of the location of the object.
2. Weight:
   • Weight is the force exerted by gravity on an object.
   • It is calculated as the product of mass and the acceleration due to gravity (\(g\)), i.e., \(W = m \times g\).
   • Weight is a vector quantity and varies depending on the gravitational field strength.

From these definitions, we can infer:

• Since mass does not change with location, it is constant.
• Weight, however, is dependent on the gravitational field which varies from one location to another, making weight variable.

Hence, the correct statement from the options given is:

"Mass is constant and Weight is variable."

This conclusion justifies why this option is correct and others are not. Other options incorrectly suggest that both properties are the same (either both constant or both variable), which contradicts fundamental physics principles.