Final answer:
The Integer field type allows users to input both positive and negative whole numbers, whereas other field types listed have more specific use cases that may not always allow for negative values.
Step-by-step explanation:
Among the options provided, b. Integer field type allows users to use both positive and negative values. An Integer is a data type used in programming languages and database management that can store whole numbers both above and below zero, without any decimal places. In contrast, an 'FX Currency' field type typically handles monetary values and may not necessarily allow negative values, as currencies are usually positive. A Percentage field type is meant to store numbers representing a percentage, which can be positive or negative, but typically this isn't its primary usage. Lastly, a Date/Time field type stores dates and times and doesn't accommodate positive or negative values in the conventional sense.