Answer:
C. But
Step-by-step explanation:
Boolean operators are the operators that may have only two outputs which are True/False, On/Off and 1/0.
"But" can also be the example of Boolean operator. It is used in the meaning of "except" or "other than".
In Boolean operators "But" can be used as "AND" operator.
for example
I am busy but I will go.
In above example but is used as and which is combining two oposite statements. as
I am busy and I will go.
Both statement oppose each other, so to make sense in English "But" is used.