An increase in the demand for led light bulbs due to changes in consumer tastes, accompanied by an increase in the supply of led light bulbs as a result of government production subsidies (which lowers the production costs to producers), will unambiguously (that is, without any doubt) result in

I believe the answer is an increase in the equilibrium quantity of LED light bulbs; the equilibrium price may increase or decrease.

As the cost to make the product came down and the demand of a certain product increase, the company would be able to obtain material to create more products, and sell more amount of it, which will lead to an increase in equilibirum quantity,