1to make things easier here are four options
(a) (i) — r ; (ii) — s; (iii) — p; (iv) — q
(b) (i) — p; (ii) — s; (iii) — q; (iv) — r
(c) (i) — p; (ii) — s; (iii) — r; (iv) — q
(d) (i) — s; (ii) — p; (iii) — q; (iv) — r
