Combinational Circuits:
Combinational circuits are a type of digital circuit where the output depends only on the present input. These circuits do not have any memory element, which means that the output is determined solely by the current input values. Combinational circuits are designed using logic gates, such as AND, OR, and NOT gates, which perform logical operations on the inputs to generate the output.

Sequential Circuits:
Sequential circuits, on the other hand, have memory elements in the form of flip-flops. These circuits have outputs that depend not only on the present input but also on the past inputs and the current state of the circuit. The output of a sequential circuit is a function of both the present input and the internal state of the circuit, which is determined by the previous inputs.

Flip Flops:
Flip flops are the basic building blocks of sequential circuits. They are bistable devices that can store a single bit of information. The output of a flip flop depends not only on the present input but also on the previous input and the current state of the flip flop. Flip flops are used to store and synchronize data in sequential circuits.

Analog Circuits:
Analog circuits are a type of circuit where the output is a continuous function of the input. These circuits use continuous signals to represent and process information. The output of an analog circuit depends on the present input as well as the previous input and the internal state of the circuit. Analog circuits are used in various applications such as amplifiers, filters, and oscillators.

Conclusion:
Among the given options, only combinatorial circuits have their output dependent only upon the present input. In combinatorial circuits, the output is a direct function of the input and does not depend on any previous inputs or internal states. Flip flops and sequential circuits have outputs that depend on both the present input and the previous inputs or internal states. Analog circuits, on the other hand, use continuous signals and have outputs that depend on both the present and previous inputs as well as the internal state of the circuit.