Final answer:
Stage Ia of cervical cancer is diagnosed through a colposcopy and biopsy of cervical tissue, while Pap smears and HPV testing are crucial for early detection and determining risk factors.
Step-by-step explanation:
The only way to diagnose stage Ia of cervical cancer is through a colposcopy and biopsy of cervical tissue (option c). A Pap smear, while useful for early detection of abnormal cells, cannot alone diagnose cervical cancer. It needs to be followed by a biopsy where a small sample of the cervical tissue is examined under a microscope for cancer cells. This is essential for confirming the presence of cancer after a suspicious Pap smear result. Imaging tests like MRI or CT scans are typically used to determine if cancer has spread, and biopsy of lymph nodes may be utilized if there is suspicion of advanced cancer spreading beyond the cervix. HPV testing is also crucial as most cases of cervical cancer are caused by human papillomavirus (HPV) infections; however, it is not a diagnostic test for the cancer stage itself but rather an indicator of potential risk.