If the length of a chain is found to be short on testing, it can be adjusted by A. straightening the links B. removing one or more small circular rings C. closing the joints of the rings if opened out D. all of the above

The correct answer is D. all of the above.

A chain is a series of links connected together. The links can be made of metal, plastic, or other materials. Chains are used for a variety of purposes, such as in jewelry, machinery, and transportation.

If the length of a chain is found to be short on testing, it can be adjusted by:

• Straightening the links: If the links are bent, they can be straightened by hand or with a tool.
• Removing one or more small circular rings: If there are too many links in the chain, one or more can be removed.
• Closing the joints of the rings if opened out: If the joints of the rings are opened out, they can be closed with a tool.

It is important to note that adjusting the length of a chain can be dangerous. If you are not familiar with how to do it, it is best to consult with a professional.