The correct answer is option 'C' - Metastable.

Explanation:
An SR latch is a basic memory element in digital circuits that stores one bit of information. It has two inputs - S (Set) and R (Reset). When both inputs are high (S = 1, R = 1), it creates a condition called "metastability."

Metastability is a state in digital circuits where the output of a latch becomes uncertain or unpredictable. In this state, the latch may settle into either a logic high or a logic low state, and the output may oscillate between these states or remain in an indeterminate state for an unknown period of time.

Several factors can contribute to metastability in an SR latch:

1. Setup and Hold Time Violation: The inputs S and R need to be stable for a certain amount of time before and after the clock signal transitions. If the setup and hold time requirements are not met, the latch can enter a metastable state.

2. Signal Skew: If the signals S and R arrive at different times due to variations in propagation delay, it can result in metastability.

3. Noise: External noise or glitches on the inputs can cause the SR latch to enter a metastable state.

4. Power Supply Variation: Variations in the power supply voltage can also contribute to metastability.

When a latch is in a metastable state, it can eventually settle into a stable state, either high or low, but the time taken to settle is unpredictable. The settling time can vary from nanoseconds to milliseconds, depending on various factors.

To avoid the issues caused by metastability, additional circuitry is used in practical designs. One common solution is to use multiple stages of latches or flip-flops to capture the output of a metastable latch and reduce the probability of propagating the metastable state further.

In conclusion, when both inputs of an SR latch are high, it enters a metastable state where the output becomes uncertain and can oscillate or remain in an indeterminate state. Metastability is an undesirable condition in digital circuits, and proper design techniques are required to mitigate its effects.