I personally have online courses, A. seems like a fitting choice in my opinion. I hope this helps.
Answer:
The correct usage is a NOR gate which is indicated in the explanation.
Explanation:
The truth table for the given two signals, namely
p=unplugged signal
q=low battery signal
can form a truth table of following form
Here p has 2 states
1 if the power supply is connected
0 otherwise
Similarly q has 2 states
0 if the battery has reached almost zero state
1 otherwise
As the condition for the Hibernate Signal is given as to only activate when the battery is low and the power supply is not connected. This indicate that the value of Hibernate signal should be 1 when both p and q are 0.
Using this condition, the truth table is formed as
unplugged signal | low battery signal | Hibernate Signal
0 | 0 | 1
0 | 1 | 0
1 | 0 | 0
1 | 1 | 0
Now the truth table of NOR is given as
a | b | a or b | ~(a or b)
0 | 0 | 0 | 1
0 | 1 | 1 | 0
1 | 0 | 1 | 0
1 | 1 | 1 | 0
This indicates that the both truth tables are same thus the NOR gate is to be used for this purpose.
