Out of the four alternatives, choose the one word which can be substituted for the given description. Speech delivered without preparation.

Introduction:
This question focuses on public speaking terminology. It asks for a single word that describes a speech delivered without prior preparation or rehearsal. Such speeches are common in debates, interviews, and casual addresses where the speaker must think on the spot.

Given Data / Assumptions:
- Description: "Speech delivered without preparation."
- Options: Rhetoric, Oration, Extempore, Maiden speech.
- We assume the emphasis is on the lack of preparation and spontaneous nature of the speech.

Concept / Approach:
The correct term for speaking without preparation is "extempore". It can be used as an adverb (to speak extempore) or as an adjective (an extempore speech). The key idea is that the speaker has not written or memorised the speech in advance but speaks spontaneously. The other options describe different aspects of speaking but do not capture this exact idea.

Step-by-Step Solution:
Step 1: Recall that "extempore" literally means "out of time" or "on the spur of the moment", referring to unprepared speech.Step 2: Compare this with "rhetoric", which refers to the art of effective or persuasive speaking in general, not necessarily unprepared.Step 3: Consider "oration", which is a formal speech, usually carefully prepared and delivered on a special occasion.Step 4: Look at "maiden speech", which refers to the first speech a person delivers in a legislative body or similar setting, again often prepared.Step 5: Conclude that only "extempore" directly expresses the idea of no preparation.

Verification / Alternative check:
Imagine a teacher asking a student to give an extempore talk on a topic, meaning the student must speak immediately without notes. This is common in language classes and public speaking training. Newspapers and event descriptions also use phrases like "an extempore speech" to highlight spontaneity. None of the other words specifically point to lack of preparation.

Why Other Options Are Wrong:
Option A, Rhetoric, is about the art and techniques of effective speaking or writing; it does not imply whether the speech is prepared or not. Option B, Oration, is a formal, often ceremonial speech, typically prepared in advance. Option D, Maiden speech, refers to a first speech, such as a new member's first address in Parliament, and says nothing about whether it was prepared. Only option C, Extempore, directly matches "speech delivered without preparation".

Common Pitfalls:
Some candidates choose "oration" because it sounds formal and they associate exam vocabulary with grand words. Others may confuse "rhetoric" with any kind of speech. To avoid these mistakes, focus on the key part of the definition, "without preparation", and recall real-life contexts where people are asked to speak extempore in competitions or language exercises.

Final Answer:
The correct one word substitute for a speech delivered without preparation is Extempore.