What can (and can) replace the D-flip-flop?

Question

Electronics

In one of the schemes, there is a need to save the state of the signal. I wanted to use a D-trigger, but suddenly there is some other option.

Answer 1

You can write down the state on a piece of paper.
In one of the schemes, hehe.

Answer 2

Like from JK trigger D the trigger can be made.
You can assemble it on discrete components if you don't want a microcircuit. :)
There is another option for perverts - the controller.
There is a variant of changeover relays, by the way, which remember the state.
The task is somehow vaguely described.