Which of the following is a correct representation of a percent?

The correct representation of a percent is given by the choice that includes the percent symbol (%) along with a numerical value. In this case, 31.4% clearly indicates a percentage, which is a way of expressing a number as a fraction of 100. This notation is commonly used to convey proportions, comparisons, and ratios in a straightforward manner.

The other options do not represent a percentage directly. For instance, 3.14 is simply a numerical value without any context of percentage. Likewise, 0.314 is a decimal representation, which can be converted to a percentage (31.4%) but does not represent it as such on its own. The number 31.4 also lacks the percent symbol, so while it represents the same numerical value, it does not communicate that it is a percentage. Therefore, 31.4% is the only option that correctly signifies a percentage.