$[$Search Algorithm$]$ Suppose you have a sorted array of $n=2^k$ distinct integers, and you are using binary search to find an element that is in the array. For complexity analysis we count only the number of comparisons to find the element.

$($a$)$ Circle all true answers.

i$.$ Best$-$case complexity is $lo{g}_{2}n.$

ii$.$ Best$-$case complexity is $1.$

iii. Worst$-$case complexity is $n.$

iv$.$ Worst$-$case complexity is $lo{g}_{2}n.$

v$.$ None of the above.

$($b$)$ Explain how you got your answer.