Order/cardinality of the group = 11.
Lagrange's theorem states that the order of every subgroup H of a group G, divides the order of G.
So what divides 11? 1 and 11.
Of order 1, there's only one subgroup, ie, {e} (identity element). This is the trivial subgroup. Every group has it.
Of order 11, the same group itself.
So, essentially there are no subgroups.
Option A