Condition on a multiple selector

I have a input that you can select A, B and or C. So you can have just A selected or B selected or A,B & C selected, etc (any combination you like).

      name: ABC
      description: Select as required.
      default: []
          multiple: true
          mode: list
            - label: A
              value: "a_a"
            - label: B
              value: "b_b"
            - label: C
              value: "c_c"

I am trying to have a condition to pass “true” if the correct one is selected. This condition only works if A is selected on it own, but it will not work if B and or C is also selected with A.

        - alias: "For A selection"
            - condition: template
              value_template: "{{ a_b_c == ['a_a'] }}"

So I need it to to be “true” if any combination includes the A in the selection and if is doesn’t have “A” selected it is “false”.