It shall be unlawful for an employer to discriminate against a person, in relation to employment in Northern Ireland.— '
(a)where that person is seeking employment—
(i)in the arrangements the employer makes for the purpose of determining who should be offered employment, or
(ii)by refusing or deliberately omitting to offer that person employment for which he applies, or
(iii)in the terms on which he offers him employment ; or
(b)where that person is employed by him—
(i)in the terms of employment which he affords him, or
(ii)in the way he affords him access to benefits or by refusing or deliberately omitting to afford him access to them, or
(iii)by dismissing him, or
(iv)by subjecting him to any other detriment.