Translate the given statement into an algebraic inequality or compound inequality: To avoid an additional charge, the sum of the length, l, width, w, and depth, d, of a piece of luggage to be checked on a commercial airline can be at most 61 inches.

a.
l + w + d greater-than 61
b.
l + w + d less-than 61
c.
l + w + d greater-than-or-equal-to 61
d.
l + w + d less-than-or-equal-to 61