When compound A is irradiated with ultraviolet light for 115 hours in pentane, an isomeric compound B

Question:

When compound A is irradiated with ultraviolet light for 115 hours in pentane, an isomeric compound B is obtained that decolorizes bromine in CH2C12 and reacts with ozone to give, after the usual workup, a compound C.

(a) Give the structure of B and the stereochemistry of both B and C.
(b) On heating to 90 °C, compound D, a stereoisomer of 5, is converted into A, but compound B is virtually inert under the same conditions. Identify compound D and account for these observations