What are the possible subsets of the set a, b?

Here are the solutions for the questions from the image:

d) The possible subsets of the set $\{a, b\}$ are
A set with $n$ elements has $2^n$ subsets. For the set $\{a, b\}$, $n=2$, so there are $2^2 = 4$ subsets. These are the empty set, sets containing one element, and the set itself.
The subsets are: $\emptyset$ (or $\{\}$), $\{a\}$, $\{b\}$, $\{a, b\}$.

Comparing this with the given options:

(i) $\{a\}, \{b\}$

(ii) $\{a\}, \{b\}, \{a, b\}$

(iii) $\{a\}, \{b\}, \{\}$

(iv) ${a},