can you please explain why E is the answer and show how the compound changes for each answer choocs ans also explain what exactly Ph3Pbr3 does?

7. Which sequence of reactions would convert Y to Z ? A) 1) H2SO4, heat; 2) MCPBA; 3) CH3Li; 4) H3O+; 5) PCC B) 1) H2SO4, heat; 2) MCPBA; 3) CH3Li; 4) H3O+; 5) CrO3/H2O C) 1) NaH; 2) EO; 3) H3O+; 4) PCC D) 1) NaH; 2) EO; 3) H3O+; 4) CrO3/H2O E) 1) Ph3PBr2; 2) Li; 3) EO; 4) H3O+; 5) PCC F) 1) Ph3PBr2; 2) Li; 3) EO; 4) H3O+; 5) CrO3/H2O