The gullible and not the … usually fall prey to tricksters.

Step 1: Analyze the question The underlined word is gullible, which means easily fooled or tricked. We need the word that is most nearly opposite in meaning and that also fits the gap in the sentence.

Step 2: Explain the concept This is an antonym question with a sentence-completion twist. Check two things:

1. Is the word opposite in meaning to "gullible"?
2. Does it make sense in the sentence, where people who are easily deceived are contrasted with another group who are not?

Step 3: Test each option

• A. unfriendly: This describes attitude, not how easily someone is tricked. It is not an antonym.
• B. carefree: This means free from worry. It is unrelated to being easily deceived.
• C. brave: This means courageous. Bravery has no direct link to being tricked, so it is not the opposite.
• D. discerning: This means having good judgment and being able to see through deception. It is the direct opposite of gullible.

Step 4: Check in the sentence "The gullible and not the discerning usually fall prey to tricksters." This makes sense: people who are easily fooled get tricked, while people with sharp judgment do not.

Answer: D. discerning

Tip: For antonym questions, first define the underlined word in simple terms (gullible = easily fooled). Then look for the option that means the reverse (hard to fool, wise, perceptive). Other antonyms of gullible include shrewd, astute, and skeptical, so learn these as a set for exams.