Who wrote the question, as it looks to me to be a poor way of giving information.
The high voltage / low voltage part is worded wrong i think..... i could be wrong myself here.
I would see it make more sense if it said a high logic and a low logic, and not high voltage and low voltage.
That way it would mean that when the board was positioned it would show a high logic or a logic "1", then when the component was loaded it would indicate another logic "1", so when all the procedures were completed then all would indicate a logic "1", then a low logic signal or logic"0" would be sent to the machine to activate it.
So the answer to the question is a circuit that requires 2 high signals to be present before it outputs a low signal.
Research logic gates, like "And gates", "Or gates", "Nand gates", "Nor gates" etc. you should be able to figure it out then.
Pete.