The following question is based on the given seven, 3-digit numbers.
(Left) 621, 443, 227, 316, 625, 118, 231 (Right)
(For example, 456: 6= digit in unit's place, 5= digit in ten's place, 4= digit in hundred's place)
NOTE - All operations to be done from left to right.
If 5 is added to the digit in ten's place of each number and 1 is subtracted from the digit in unit's place of each number, which digit will be repeated the greatest number of times in the transformed number series thus formed?

Given :   (Left) 621, 443, 227, 316, 625, 118, 231 (Right)

621 → 670

Ten's place: 2 + 5 = 7

Unit's place: 1 - 1 = 0

443 → 492

Ten's place: 4 + 5 = 9

Unit's place: 3 - 1 = 2

227 → 276

Ten's place: 2 + 5 = 7

Unit's place: 7 - 1 = 6

316 → 365

Ten's place: 1 + 5 = 6

Unit's place: 6 - 1 = 5

625 → 674

Ten's place: 2 + 5 = 7

Unit's place: 5 - 1 = 4

118 → 167

Ten's place: 1 + 5 = 6

Unit's place: 8 - 1 = 7

231 → 280

Ten's place: 3 + 5 = 8

Unit's place: 1 - 1 = 0

(Left)  670, 492, 276, 365, 674, 167, 280 (Right)

6 is the digit which repeated most number of time.

Thus, correct option is (c).