The correct sentence that uses hyphenation conventions is: "The contractor kept the load-bearing wall."
The other sentences either have inconsistencies in hyphenation or incorrect hyphenation. For example, "salt-and-pepper" is correctly hyphenated, but it's repeated twice, and "quick-wit" should be "quick wit" without a hyphen. Additionally, "two faced-woman" should not have a hyphen and should be "two-faced woman."