(a)hv, conrotatory opening and $\Delta$, disrotatory opening.
(b)$\mathrm{h} v$, disrotatory opening and $\Delta$, conrotatory opening.
(c)$\Delta$, conrotatory opening and $\mathrm{h} v$, disrotatory opening.
(d)$\Delta$, disrotatory opening and $h \nu$, conrotatory opening.