For the reaction below write all the possible products. Decide the relationship between all the isomers and decide if the reaction is specific or selective. Please take into consideration the region and stereo control.

2. Compound A undergoes a cascade of electrocyclic reactions to give compound B under thermal conditions and C under photochemical conditions. Compounds B and C can undergo a further cycloaddition reaction under photochemical conditions to give compounds D and E, respectively.

I. Write the chemical structures of all the possible isomers for compounds B, C, D, and E.

II. For the cascade of your choice (A-B-D or A-C-E), explain in detail the reaction mechanism.

III. Consider the Woodward-Hoffmann rules and frontier molecular orbital theory to suggest whether the reaction is allowed or forbidden.