The discovery of the remains of a dockyard at Lothal prove that the people of Indus valley had- (a) international trade relations.
(b) expertise in ship building,
(c) an organised naval force.
(d) flourishing trade within India.

(a) international trade relations.

Explanation:

The discovery of the remains of a dockyard at Lothal prove that the people of Indus valley had "international trade relations."

The remains of the dockyard at Lothal were discovered in 1954. Following the scientific analysis of the Archeological Survey of India, and later discovery of foraminifera (marine microfossils) and salt by the National Institute of Oceanography, Goa, it was concluded that Lothal was a significant and prosperous trade centre in olden ages. And the trading activities involved international partners including the west Asia and Africa.

the first historical instance of china engaging in internationalism was during the han dynasty.[1] at the start of the han dynasty, the huns in the north were attacking the frontiers of han and trying to obtain riches. emperor wu of han wanted to gain an alliance with a country called dayuezhi so the two countries could join together and fight against the huns.[2] to obtain this alliance, emperor wu sent zhang qian to the west to establish economic and cultural connections.[2] history records that during the han dynasty there were four primary avenues of contact between china and europe. they included the northern land route, the central land route, the southern sea route, and the far southern sea route.[1] the most famous of these routes is the central land route, or the classical silk road, comprising a network of roads stretching from northwest china to the ports of syria and the black sea, which passed through the oasis of the turkestans and northern persia.[1] the silk road was significant for chinese emperors because it provided dominance over central asia by developing resources and provided new markets for the export of china's most valuable resources.[1]

the answer to fill in the blank in this question would be the word resource, it is defined as the money, material or people (since human resource is a very valuable good) that a company or a person has at disposition (meaning they can use the resource as they see fit), to be able to complete a task or achieve a goal.