$15.$ The divide$-$and$-$conquer strategy breaks a problem into:

a$)$ Independent subproblems

b$)$ Overlapping subproblems

c$)$ Single subproblem

d$)$ Non$-$overlapping and dependent subproblems

$16.$ In Quick Sort, the pivot element is chosen to:

a$)$ Minimize comparisons

b$)$ Maximize comparisons

c$)$ Partition the array

d$)$ Merge subarrays

$17.$ Which sorting algorithm is more efficient for large datasets?

a$)$ Merge Sort

b$)$ Insertion Sort

c$)$ Bubble Sort

d$)$ Selection Sort

$18.$ Which step is unique to Quick Sort compared to Merge Sort?

a$)$ Divide

b$)$ Conquer

c$)$ Choose a pivot for partitioning

d$)$ Combine

$19.$ What does the "combine" step do in Merge Sort?

a$)$ Finds the pivot element

b$)$ Merges two sorted subarrays

c$)$ Divides the array into smaller parts

d$)$ Sorts elements directly

$20.$ The recurrence relation for Merge Sort is:

a$)()=2($ #

$!)+()$

b$)()=(1)+(1)$

c$)()=($ #

$!)+(!)$

d$)()=3($ #

$")+()$

$21.$ Dynamic programming is used to solve problems with:

a$)$ Greedy$-$choice property

b$)$ Optimal substructure and overlapping subproblems

c$)$ Optimal substructure only

d$)$ Independent subproblems