Step 1: Determine Time Complexities.
- Bubble Sort (Worst Case) (A): Time complexity is $O(n^2)$.
- Singly Linked List Head Deletion (B): Time complexity is $O(1)$.
- Binary Search (C): Time complexity is $O(\log n)$.
- Merge Sort (Worst Case) (D): Time complexity is $O(n \log n)$.
Step 2: Order by Time Complexity (Ascending).
The correct order from lowest to highest is: - (B) Deleting head node: $O(1)$ - (C) Binary search: $O(\log n)$ - (D) Merge sort: $O(n \log n)$ - (A) Bubble sort (worst case): $O(n^2)$
Step 3: Final Order.
The correct sequence is (B), (C), (D), (A).