Step 1: Understanding the Question:
This question tests the candidate's understanding of common English idioms and phrases.
The idiom in focus is 'pie in the sky'.
We must determine its meaning based on its figurative usage.
Step 2: Key Approach:
Retrieve the figurative meaning of the idiom by looking at its metaphorical context (something unreachable in the sky).
Deduce its modern application in political and social speech contexts.
Step 3: Detailed Explanation:
• Origin and Meaning of 'Pie in the Sky':
The phrase 'pie in the sky' originated from a 1911 song by Joe Hill, which criticized preachers promising rewards in heaven (the sky) while working class people suffered on Earth.
Figuratively, it refers to an empty promise, an illusion, or a dream that is pleasant to contemplate but extremely unlikely to ever be realized.
• Analyzing the Options:
Option A ('partially implemented') suggests some progress, which does not fit the idea of an empty or impossible promise.
Option B ('a practical one') is the opposite of the idiom's meaning.
Option C ('an unrealistic hope') perfectly matches the definition of something desirable but completely unattainable or highly unrealistic.
Option D ('hidden agenda') means a secret motive, which is distinct from an unrealistic promise.
Step 4: Final Answer:
Thus, the correct meaning of 'a pie in the sky' is 'an unrealistic hope'.