Final answer:
For a woman at risk for breast cancer, a diet rich in cruciferous vegetables containing sulforaphane and other glucosinolates, which fall under the category of thiols, is recommended based on their potential anti-cancer properties as part of a broad cancer-preventive dietary approach.
Step-by-step explanation:
The recommendation for a woman at risk for breast cancer should be focused on a diet rich in phytochemicals that have shown potential in reducing cancer risk. While lignans, found in seeds like flax and certain whole grains, have some association with breast cancer prevention, it's the compounds in cruciferous vegetables such as sulforaphane from broccoli and other glucosinolates that have shown significant anti-cancer properties. These compounds help protect cells from DNA damage, inactivate carcinogens, and inhibit tumor growth and spread. Although research on humans has provided mixed results, the overall dietary recommendations by organizations such as the American Institute for Cancer Research emphasize consuming more fruits, vegetables, fiber, and legumes while limiting alcohol intake, as these dietary habits are correlated with a reduced risk of various cancers.
Given the information provided and its focus on phytochemicals with evidence of cancer prevention qualities, the most relevant choice would likely involve consuming foods rich in sulforaphane and other glucosinolates, implying a recommendation toward thiols found in cruciferous vegetables.