Which prefix indicates something that is considered to be in excess?

The prefix "ultra-" signifies something that is beyond or in excess of the usual limits, making it the correct choice. This prefix is commonly used in various contexts to denote exceeding standards, capabilities, or quantities. For example, "ultrasonic" refers to sound waves that are above the audible range, and "ultra-processed" describes food that has undergone extensive processing beyond natural food preparations.

In contrast, other prefixes like "trans-" generally refer to something that crosses or moves through a border or boundary, while "super-" also can indicate superiority but is more about elevation or exceeding in a qualitative sense rather than strictly in excess. Lastly, "tachy-" typically relates to speed and is often used in medical terms to describe rapid processes but does not inherently convey the notion of excess.