'FCE / B2 First Word Formation Practice Exam 2025 – Comprehensive Guide to Mastering Your Certification!'

The noun form of "perform" is "performance." This term specifically refers to the act of performing, which is a key distinction from the other options provided. "Performance" can denote a variety of contexts, such as a theatrical show, a musical event, or an evaluation of someone's work or behavior. It captures the essence of the action in noun form, allowing it to be used to describe events, evaluations, or presentations.

In contrast, "performer" designates a person who performs, which is derived from the verb but represents an individual rather than the action itself. "Performable," while a real word, is an adjective indicating something that is capable of being performed, thus straying from the request for a noun form. Lastly, "performing" is the present participle of the verb, used in contexts describing the action as it unfolds, but it does not represent a discrete noun relating to the act of performing.

"Performance" clearly aligns with the request for the noun form of "perform," making it the appropriate choice.