Arrange the following levels of interrupt protection within the Linux Kernel in order of increasing priority:
(A) user mode programs
(B) bottom half interrupt handlers
(C) kernel system service routines
(D) top half interrupt handlers

1. A(A) (A), (B), (D), (C)
2. B(B) (A), (C), (B), (D)
3. C(C) (A), (C), (D), (B)
4. D(D) (D), (A), (C), (B)

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