Which of the following is a subgroup of the group G= 1,2,3,4,5,6 under 7 ?

Step-by-step solution

Option (c) cannot be subgroup as identity ' 1 ' is not present. Option (d) cannot be a subgroup of 2 ₇ 3=6 1,2,3 . Option (a) cannot be a subgroup as 2 ₇ 6=5 2,6,1 . So, option (b) is a subgroup.