What upward force counteracts the weight of an object in a fluid?

The upward force that counteracts the weight of an object in a fluid is known as lift. Lift is generated when the flow of fluid around an object creates a pressure difference between the top and bottom surfaces of the object submerged in the fluid. This principle is crucial in various applications, particularly in aviation, where wings generate lift to allow aircraft to rise against the force of gravity.

While drag refers to the resistance experienced by an object moving through a fluid, weight pertains to the gravitational force acting on the object downward, and thrust is the force that propels an object forward. None of these forces serve the specific function of opposing weight through an upward motion generated by fluid dynamics, making lift the appropriate answer for this question.