Prenatal diagnosis — the needle-based procedure used mainly to detect fetal chromosomal or genetic abnormalities is called:

Introduction / Context:
Early and accurate prenatal diagnosis helps identify chromosomal abnormalities, genetic disorders, and certain fetal infections. Among the invasive techniques, amniocentesis is a standard, needle-based method for sampling amniotic fluid under ultrasound guidance.

Given Data / Assumptions:

• Procedure involves a needle and aims at diagnosing fetal defects.
• Amniotic fluid contains fetal cells and biochemical markers.
• Timing is typically in the second trimester, though later diagnostic taps occur when indicated.

Concept / Approach:

Amniocentesis withdraws amniotic fluid for karyotyping, microarray, specific gene tests, and biochemical analyses (e.g., alpha-fetoprotein). It complements noninvasive screening by providing confirmatory diagnostic data with high specificity.

Step-by-Step Solution:

Verification / Alternative check:

Clinical guidelines list amniocentesis and chorionic villus sampling (CVS) as primary invasive diagnostics; the question cues the amniotic fluid–based needle test.

Why Other Options Are Wrong:

(b) Ectogenesis is not a diagnostic procedure. (c) Transplantation is unrelated. (d) “All” cannot be correct as two options are irrelevant.

Common Pitfalls:

Confusing CVS (placental biopsy) with amniocentesis; both use needles but sample different tissues and are performed at different gestational windows.

Final Answer:

Amniocentesis