Solve the following compound inequality: 4 less-than-or-equal-to x + 4 less-than-or-equal-to 12. a. 0 less-than-or-equal-to x less-than-or-equal-to 8 c. 8 less-than-or-equal-to x less-than-or-equal-to 16 b. x less-than-or-equal-to 8 d. no solution