With reference to the period of Gupta dynasty in ancient India, the towns Ghantasala, Kadura and Chaul were well known as

Names several western-coast ports that 'facilitated trade' and explicitly lists Chaul as a port involved in trade.

A student could treat Chaul as plausibly an important Gupta-period trade port and then check maps and port-lists to locate Chaul and compare its known medieval maritime role.

States the Gupta era participated in long-distance maritime trade via the Indian Ocean, exporting textiles, spices, ivory and gemstones.

Use this rule (Gupta-era ports connected to Mediterranean, SE Asia, China) to test whether named coastal sites (Ghantasala, Kadura, Chaul) lie on likely maritime routes and thus could handle foreign trade.

Archaeological and textual evidence shows Gupta-era contacts with distant regions (e.g., Indonesia), implying functioning maritime links and ports supporting such contact.

Combine this pattern with geographic knowledge of east- and west-coast port locations to judge which named sites (Ghantasala on the east coast, Chaul on the west) fit the maritime-contact pattern.

Describes flourishing mining and metallurgy producing tradable metals and goods during the Gupta period, creating exportable commodities that ports would handle.

A student could infer that regions producing exportable goods would use nearby ports for foreign trade and then check which named ports served those production areas.