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.
Utilize the input text as a context reference, choose the right relationship between 'Polyus' and 'mining' from the options.
Options: industry, headquarters location, chief executive officer, employer