Final answer:
To decide between supra-supra/supra-antara and thermally/photochemically for a sigmatropic rearrangement, consider the conditions under which the rearrangement occurs.
Step-by-step explanation:
In order to decide between supra-supra/supra-antara and thermally/photochemically when the educt and product of a sigmatropic rearrangement is given, you need to consider the conditions under which the rearrangement occurs.
If the reaction occurs under thermal conditions, it is more likely to be supra-supra/supra-antara. This means that the reaction occurs concertedly and the migrating group retains its stereochemistry.
If the reaction occurs under photochemical conditions, it is more likely to be thermally driven. This means that the reaction occurs via a stepwise process involving an intermediate, where the migrating group may undergo inversion of stereochemistry.