This book is a practical guide for candidates intending to sit paper B of the European Qualifying Examination on how to respond to an office action issued by an EPO Examiner. It also provides a general introduction on the procedure up to grant of a European Patent and a detailed elaboration on how to deal with paper B of the EQE. Particularly, on the basis of the actual papers B of 2017-2019, which papers are unitary papers and no longer differentiate between the technical fields of Electricity/Mechanics and Chemistry, useful approaches and key aspects for the solving of these papers are given. In addition, examples are taken from papers of a few years before. These additional papers do differentiate between the fields of Electricity/Mechanics and Chemistry, but already anticipate on the new single papers. From 2025, extensive changes to the current EQE and the corresponding preparation courses are planned. In 2025, the changes will only affect the current preliminary examination, which will be replaced by a so-called 'foundation paper', while examination papers A, B, C and D will remain current. These will then be progressively replaced by new papers (M1 - M4) in 2026 and 2027. The new format of the EQE will have an impact on the further design or continuation of the ABCD-Books.