**Highest** { best-case runtime (for that algorithm!) } complexity is the one which **takes the longest time to complete**. The question wants you to find the highest, which is the slowest algorithm from the options. So, it is obviously it is $O(n^2)$.

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Which of the below given sorting techniques has highest best-case runtime complexity.

**(A)** Quick sort

**(B)** Selection sort

**(C)** Insertion sort

**(D)** Bubble sort

**Answer:** **(B)**

**Explanation:**

Quick sort best case time complexity is Ο(n logn)

Selection sort best case time complexity is Ο(n^2 )

Insertion sort best case time complexity is Ο(n)

Bubble sort best case time complexity is Ο(n)

Source: GeeksforGeeks

https://www.geeksforgeeks.org/gate-gate-mock-2017-question-12/

I did not understand this as best case time should be O(n) sorting method what does highest best cases mean?