The common difference between consecutive integers is 1
Recall that integers are sets of whole numbers. If the least of 5 consecutive integers is l, it means that the 5 consecutive integers are
l, l + 1, l + 2, l + 3, l + 4
If the greatest integer is g, then
g = l + 4
Thus,
(l + g)/2 = (l + l + 4)/2 = (2l + 4)/2
Factorising 2 out, we have
2(l + 2)/2
= l + 2
Option C is correct
