What is the relationship between Polyus and mining in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

However, with the current uncertainty within the mining sector, it seems prudent to stick to companies that are profitable now and, with Petra Diamonds offering stronger growth prospects at a more appealing price than Polyus Gold, it seems to be the pick of the three stocks at the present time.

Answer: industry