The correct answer is (B) Deep mire, mud hole, an area of soft, muddy ground; quagmire. Also, a swamp; swamp-like area; marshy place.

Slough comes from Old English slóh.

Examples of use:

• The farm's slough attracted geese and other birds during their migrations.
• The water of the slough on his farm was home to both shrimp and fish.