**Core Concept**
Carcinoma cervix, also known as cervical cancer, is a malignancy of the cervix uteri. Early detection is crucial for effective management and treatment. The ideal investigation should be highly sensitive and specific for detecting pre-invasive and early invasive lesions.

**Why the Correct Answer is Right**
Liquid-based cytology (Pap smear) and high-resolution colposcopy are essential tools in the early detection of cervical cancer. However, the most sensitive and specific investigation for early-stage cervical cancer is the **human papillomavirus (HPV) DNA test**, particularly the **HPV 16 and 18 genotyping**. This test detects the presence of high-risk HPV types that are responsible for the majority of cervical cancer cases. It is often used in conjunction with the Pap smear to improve detection rates.

**Why Each Wrong Option is Incorrect**
**Option A:** Colonoscopy is a diagnostic tool for colorectal cancer and is not relevant to cervical cancer diagnosis.
**Option B:** Chest X-ray may be used in the staging of cervical cancer but is not a diagnostic tool for early-stage disease.
**Option C:** Computed Tomography (CT) scan and Magnetic Resonance Imaging (MRI) are used in the staging of cervical cancer, but they are not the best initial investigations for early-stage disease.

**Clinical Pearl / High-Yield Fact**
The HPV vaccine has been shown to be effective in preventing cervical cancer by targeting the high-risk HPV types. It is recommended for all females between 9 and 26 years of age.

**Correct Answer: D. HPV DNA test**