Which statement correctly describes static and dynamic data structures?

• A. Static data structures have fixed size; dynamic structures can grow or shrink at runtime
• B. Static structures require runtime allocation; dynamic structures are compile-time
• C. Static data structures are always faster than dynamic
• D. Static structures use heap memory; dynamic use stack

Answer: (A)

Understanding how capacity is managed helps here. Static data structures have a fixed size determined when they’re created, so they can hold only up to that many elements and don’t grow automatically as you add data. Dynamic data structures are designed to grow or shrink at runtime by allocating or freeing memory as needed, so their capacity can change during the program’s execution. This is why the statement describing static structures as fixed-size and dynamic structures as resizable at runtime is correct.

For context, a fixed-size array is a typical static structure: it allocates space for a set number of elements and that space isn’t expanded unless you create a new, larger structure. A dynamic structure—like a dynamic array or a linked list—adjusts its memory usage as elements are added or removed.

The other ideas aren’t accurate in general. Static structures don’t inherently require runtime allocation for their elements to exist, and dynamic structures don’t rely solely on compile-time decisions. Saying static structures are always faster ignores the practical trade-offs and possible resizing costs in dynamic structures. Also, where the memory for these structures lives isn’t fixed across languages: static structures can live on the stack, the heap, or in a data segment, and dynamic structures typically involve runtime allocations, often on the heap, but not as an absolute rule.