1. The problem asks what the notation $\{a, b, c, \ldots, z\}$ represents. 2. This notation is a set notation in mathematics, where elements inside curly braces $\{\}$ represent members of a set. 3. The elements $a, b, c, \ldots, z$ indicate a sequence starting from $a$ to $z$, including all letters in between. 4. The ellipsis $\ldots$ means "and so on," implying all elements from $a$ through $z$ are included. 5. Since $a$ through $z$ are the 26 lowercase English letters, the set contains all these letters. 6. Therefore, the notation $\{a, b, c, \ldots, z\}$ represents a finite set containing all lowercase English letters. Final answer: a. A set containing all lowercase English letters