UPSC NDA I 2019 Mathematics Solved Paper

Concept:The power set of a set $A$ is the set of all possible subsets of $A$.Explanation:Given $A = \{ \lambda, \{ \lambda, \mu \} \}$, the set has two elements: $\lambda$ and $\{ \lambda, \mu \}$.The number of subsets of $A$ is $2^{2} = 4$, where $2$ is the number of elements in $A$.List all subsets:• $\phi$ (empty set)• $\{ \lambda \}$ (subset containing only $\lambda$)• $\{ \{ \lambda, \mu \} \}$ (subset containing the element $\{ \lambda, \mu \}$)• $\{ \lambda, \{ \lambda, \mu \} \}$ (the set itself)Thus, the power set $P(A) = \{ \phi, \{ \lambda \}, \{ \{ \lambda, \mu \} \}, \{ \lambda, \{ \lambda, \mu \} \} \}$.This matches option B.Answer:Option B.