Vocabulary in context: in the passage about thought, word and deed, choose the adjective that best completes the phrase "thought is the most ______ and powerful force."

Introduction / Context:
The next passage contrasts thought, word and deed and emphasises the special power of thought. It states that success is achieved twice, once in the mind and then in the real world. The sentence with the blank says, "Of the three activities of thought, word and deed, perhaps thought is the most ______ and powerful force." The missing adjective must reinforce the idea that thought has great strength and influence.

Given Data / Assumptions:
Thought is called a powerful force in the very same sentence.
The passage later mentions laser like energy of thought that seeks a target, and the importance of positive thinking.
Options are potent, fragile, ineffective, disabled and passive.
The overall message is that positive thought can be used for welfare and success.

Concept / Approach:
Potent is an adjective that means very strong, effective or powerful. When combined with powerful force, it emphasises that thought has great strength. Fragile means easily broken, ineffective means not producing results, disabled suggests lacking ability, and passive means not active. None of these negative or weak adjectives fit with the description of thought as powerful or with the metaphor of laser like energy. Therefore potent is the only word that fits both literal meaning and the tone of the passage.

Step-by-Step Solution:
Step 1: Note that the sentence already includes the phrase powerful force, so the blank must be filled by a word that agrees with this idea. Step 2: Understand that the passage argues that thought is central to success and has laser like energy, which implies high strength. Step 3: Test potent: thought is the most potent and powerful force. This is a natural collocation in English and conveys the message that thought is extremely strong. Step 4: Test fragile, ineffective, disabled and passive and see that they would contradict the words powerful force. Step 5: Therefore choose potent as the correct answer.

Verification / Alternative check:
If we insert potent and read the surrounding lines about success being achieved first in the mind and then in the outer world, everything is consistent. Thought is presented as the origin of words and deeds and as a force that can be harnessed positively. Any adjective that suggests weakness would clash with this consistent message. Potent is widely used in such motivational or philosophical writing, for example potent ideas or potent influences, which supports its selection.

Why Other Options Are Wrong:
Fragile would imply that thought is easily broken and therefore unreliable as a foundation for success. Ineffective would imply that thought does not produce results, contradicting the two stage success idea. Disabled suggests impairment or inability and is inappropriate in this metaphorical context. Passive would present thought as inactive, whereas the passage describes it as actively seeking a target. The additional option passive therefore also does not fit.

Common Pitfalls:
This is a relatively straightforward vocabulary item, but some students may not know the word potent and may guess blindly. Learning common collocations such as potent symbol, potent force and potent influence can greatly help with such questions. When in doubt, always check whether the candidate word matches both the local phrase and the overall tone of the passage.

Final Answer:
The adjective that correctly completes the phrase is potent, so option potent is correct.