Let $A = \{1, 2, \{3, 4\}, 5\}$. Which statement is **TRUE**?
A$\{3, 4\} \subset A$
B$\{3, 4\} \in A$
C$1 \subset A$
D$\phi \in A$
Answer & Solution
Correct answer: B. $\{3, 4\} \in A$
The element $\{3, 4\}$ is itself one of the four members of $A$. So $\{3, 4\} \in A$ (membership), but $\{3, 4\} \not\subset A$ (because $3 \notin A$ — only the *pair* $\{3,4\}$ is an element).
- **A** confuses $\in$ with $\subset$.
- **C** uses $\subset$ where it should be $\in$.
- **D** is false — $\phi$ is not listed as a member of $A$.
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