Select the option that best expresses the meaning of the idiom: Run out of steam.

Introduction / Context:
Idioms are fixed expressions whose meanings cannot always be understood from the literal meanings of the individual words. Run out of steam is an idiom that originally comes from the age of steam engines, but is now widely used in everyday English to describe people and projects. The question tests whether you know the figurative meaning of this expression.

Given Data / Assumptions:

• Idiom: Run out of steam.
• Options: To lose impetus or enthusiasm; To work quickly like a machine; To give up easily; no more money to spend.
• We assume the phrase is used in a general context about effort, energy, or motivation.
• We must pick the option closest to the idiomatic sense, not the literal picture of steam running out.

Concept / Approach:
Literally, a steam engine that runs out of steam loses the pressure needed to move and gradually slows down or stops. Metaphorically, when a person or project runs out of steam, it means they lose energy, momentum, or enthusiasm, causing progress to slow or halt. It does not directly refer to speed like a machine or to giving up at the first sign of trouble, and it definitely does not relate to money unless used in a specific financial metaphor.

Step-by-Step Solution:
Step 1: Visualise a steam engine whose steam supply is exhausted; it slows down and eventually stops moving. Step 2: Map that image to human situations: a person working on a project may become tired or lose interest, so their effort declines. Step 3: Examine option A: To lose impetus or enthusiasm. This directly describes a decline in energy and motivation, just like the fading power of a steam engine. Step 4: Examine option B: To work quickly like a machine. This is the opposite of slowing down and clearly does not match the idea of running out of steam. Step 5: Examine option C: To give up easily. Running out of steam implies a gradual loss of drive after some effort, not an immediate surrender at the start. Step 6: Examine option D: no more money to spend. While people sometimes use similar phrases about money, the idiom run out of steam is about energy and motivation, not finances. Step 7: Conclude that option A is the correct interpretation.

Verification / Alternative check:
Consider typical usage: The team started well but ran out of steam in the second half of the match, or The campaign ran out of steam after a few weeks. In these examples, nobody is talking about money or initial weakness; instead, the examples describe a loss of momentum after an energetic start. The subjects did not give up easily; they tried for some time and then slowed down. This perfectly aligns with losing impetus or enthusiasm.

Why Other Options Are Wrong:
To work quickly like a machine is wrong because it suggests high energy and speed, not a loss of power. To give up easily is wrong because running out of steam implies prior effort and then decline, not instant surrender. No more money to spend is wrong because the idiom does not directly refer to financial resources, even though steam is a kind of fuel in the original literal sense.

Common Pitfalls:
A common error is to connect steam with machinery and choose the option about working quickly like a machine, but this ignores the phrase out of, which signals depletion. Another pitfall is equating any expression about running out with money shortages, but here the idiom has a broader, metaphorical meaning about energy and drive. To master idioms, it helps to see them in context rather than guessing from individual words.

Final Answer:
Run out of steam means to lose impetus or enthusiasm.