In statistics out of 100, the marks of 21 students in final exams are as 90, 95, 95, 94, 90, 85, 84, 83, 85, 81, 92, 93, 82, 78, 79, 81, 80, 82, 85, 76, 85, then the mode of data is:

The correct answer is Option 4: 85.

Understanding Mode in Statistics:
In statistics, the mode of a set of data values is the value that appears most frequently. If a number occurs more times than any other number in the dataset, that number is the mode.

Step 1: List the given data points:
The marks of the 21 students are:
90, 95, 95, 94, 90, 85, 84, 83, 85, 81, 92, 93, 82, 78, 79, 81, 80, 82, 85, 76, 85

Step 2: Count the frequency of each score:
Let's count how many times each mark appears in the dataset:

76 occurs 1 time
78 occurs 1 time
79 occurs 1 time
80 occurs 1 time
81 occurs 2 times (81, 81)
82 occurs 2 times (82, 82)
83 occurs 1 time
84 occurs 1 time
85 occurs 4 times (85, 85, 85, 85)
90 occurs 2 times (90, 90)
92 occurs 1 time
93 occurs 1 time
94 occurs 1 time
95 occurs 2 times (95, 95)

Step 3: Identify the mode:
By comparing the frequencies of all marks, we see that the mark 85 appears 4 times, which is more frequent than any other mark in the list.

Therefore, the mode of the given data is 85.