**Core Concept**
The management of postcoital bleeding in a 35-year-old lady involves evaluating for potential cervical or vaginal pathology, such as cervical cancer or cervical intraepithelial neoplasia (CIN). This requires a detailed examination of the cervix to identify any lesions or abnormalities.

**Why the Correct Answer is Right**
Colposcopy is the correct choice because it allows for a magnified examination of the cervix, vagina, and vulva using a colposcope. This helps to identify any suspicious lesions or abnormalities that may not be visible to the naked eye. During colposcopy, the healthcare provider can also apply a solution of acetic acid or Lugol's iodine to highlight any areas of abnormal cellular activity. Colposcopy is a crucial diagnostic tool for evaluating postcoital bleeding and other symptoms suggestive of cervical cancer or CIN.

**Why Each Wrong Option is Incorrect**
**Option A:** Clinical examination and Pap smear are essential components of cervical cancer screening, but they may not be sufficient to evaluate postcoital bleeding, which requires a more detailed examination of the cervix.
**Option B:** Visual examination with Lugol iodine is a technique used during colposcopy to highlight areas of abnormal cellular activity, but it is not a standalone diagnostic tool.
**Option C:** Visual examination with acetic acid is another technique used during colposcopy to highlight abnormal areas, but like Lugol iodine, it is not a standalone diagnostic tool.

**Clinical Pearl / High-Yield Fact**
A key aspect of colposcopy is the use of the Bethesda System for Reporting Cervical/Vaginal Cytologic Diagnoses, which provides a standardized approach to reporting colposcopy findings and guiding further management.

**✓ Correct Answer: D. Colposcopy**