Which of the following are involved in the weak force?

Which of the following are involved in the weak force?

    a core which emits neutrinos

    Fermi's β-decay theory

    26Al

    undetectable with balloon-borne detectors

    Gamow-Teller interactions

    steady enough emission to be used as a standard for X-ray emission

    observed with delta-rays in 1731

    M. Fierz