Topic: Synonyms,

Best Answer Explained in Below-:

The term "extempore" refers to something that is done spontaneously or without preparation, often in a manner that is improvisational. When analyzing the options provided, "impromptu" (option C) aligns closely with this definition. Both terms imply an element of spontaneity and a lack of premeditation, signifying an action taken on the spot or without prior planning.

Conversely, "planned" (option A) suggests the opposite of extempore, as it involves forethought and organization. "Improvise" (option B) also relates to unprepared performance, but it may imply a level of creativity or on-the-spot crafting that’s not as directly synonymous as "impromptu." Lastly, "immediate" (option D) implies something occurring right away but doesn’t necessarily carry the connotation of spontaneity or lack of preparation.

Thus, “impromptu” is the most accurate synonym for "extempore," as both convey the idea of actions or performances that are carried out without advance notice or arrangement.