JK Flip-Flop in Toggle Mode:

Explanation:
A JK flip-flop is a sequential circuit element that can store one bit of information. It has two inputs, J (set) and K (reset), and two outputs, Q (output) and Q' (complement of output). The behavior of a JK flip-flop depends on the inputs and the state of the flip-flop.

In toggle mode, the output of a JK flip-flop toggles (changes state) whenever both J and K inputs are high (1). The flip-flop retains its current state when both J and K inputs are low (0). The toggle mode is also known as the "flip-flop" mode or "T" mode.

Options:
Let's analyze the given options:

a) J = 0, K = 1:
When J = 0 and K = 1, the flip-flop operates in the "reset" mode. The output Q will be 0, regardless of its previous state. This option does not represent the toggle mode.

b) J = 1, K = 1:
When J = 1 and K = 1, the flip-flop operates in the "toggle" mode. The output Q will toggle (change state) with each clock pulse. This option represents the toggle mode correctly.

c) J = 0, K = 0:
When J = 0 and K = 0, the flip-flop retains its current state. The output Q will remain unchanged, regardless of its previous state. This option does not represent the toggle mode.

d) J = 1, K = 0:
When J = 1 and K = 0, the flip-flop operates in the "set" mode. The output Q will be forced to 1, regardless of its previous state. This option does not represent the toggle mode.

Conclusion:
From the given options, option 'B' (J = 1, K = 1) represents the correct input values for a JK flip-flop to operate in the toggle mode. In this mode, the output Q will toggle (change state) with each clock pulse.