Why is Shell sort called as a generalization of Insertion sort?
(a) Shell sort allows an exchange of far items whereas insertion sort moves elements by one position
(b) Improved lower bound analysis
(c) Insertion is more efficient than any other algorithms
(d) Shell sort performs internal sorting
This question was addressed to me in an interview for internship.
My doubt stems from Shell sort topic in chapter Sorting of Data Structures & Algorithms II