C

In adult-type (post-ductal) coarctation, high-pressure blood from the subclavian → internal thoracic (mammary) artery passes into the anterior intercostal arteries, joins the enlarged posterior intercostals, and then continues via the superior and inferior epigastric arteries to reach the external iliac arteries and lower limbs; thus the key collateral channels are the intercostal and superior epigastric arteries, not the other options [Huhmann, 1976, PMID 964150; Woodring, 1985, PMID 3871142].