Final answer:
CEA (carcinoembryonic antigen) is the tumor marker widely used for the detection and monitoring of colorectal cancers.
Step-by-step explanation:
The tumor marker widely used for the detection of colorectal cancers is d) CEA (carcinoembryonic antigen). Tissue-specific markers like CEA are often utilized in the follow-up of treated cancer patients to monitor the progress of the disease or the response to treatment. While the presence of CEA is not exclusive to colorectal cancers, given its association with the gastrointestinal system, it is considered a go-to biomarker for detecting potential recurrences or monitoring response to therapy in individuals with a history of colorectal cancer. Proteomics is also advancing the use of protein biomarkers for individualizing cancer treatment plans and detecting disease recurrence.