The domain of the function in this scenario is determined by the possible values of the account balance \( x \) that could affect whether the account is locked or not.
Since the account locks if the balance is less than or equal to -100 (indicating that the customer owes more than $100), we are interested in values of \( x \) that can be less than or equal to -100 or greater than -100 (which would mean they owe less than $100).
Therefore, the domain of this function should include all balances that are less than or equal to -100 and anything above that.
The correct response is:
[−100, ∞]
So, the account could be locked if \( x \leq -100 \) or unlocked if \( x > -100 \). The necessary values to account for this are from -100 to +∞, including -100 itself.