As a beginner, this might not make too much sense, but it's worth providing a LINQ based solution.
x
.GroupBy(i => i) //place all identical values into groups
.OrderByDescending(g => g.Count()) //order groups by the size of the group desc
.Select(g => g.Key) //key of the group is representative of items in the group
.First() //first in the list is the most frequent (modal) value
