For positive logic, what is the minimum signal level necessary to activate an OR gate?

In the context of positive logic, an OR gate is a digital logic gate that outputs a high signal (logic level '1') if at least one of its inputs is high (logic level '1'). Therefore, the minimum signal level necessary to activate the gate is any input that is considered high.

When any input to the OR gate receives a high signal, it guarantees that the output will be high as well, regardless of the state of the other inputs. This characteristic defines how the OR gate functions within digital circuits, making the requirement for at least one high input sufficient for activation.

The other choices do not meet the condition required for the OR gate to activate. Low inputs do not trigger the output to be high, and requiring two or more inputs to be either low or high would not reflect the true nature of an OR gate, which functions with just one high input among any number of inputs.