When you've decided to buy an item at a department store, which of the following do you say to the salesperson?

a. I'll take it.
b. I'll buy it.
c. I'll have it.
d. I'll get it.

Are all of the above possible?
In my experience, "I'll take it" is most common. "I'll buy it" is somewhat less common.
The other two would require special context.
I'll take it

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