Importance of sections?

Hi Friends I wanted to know if writing the sub-section and clauses is necessary while attempting exams in CA Final specially Law, audit, DT and IDT. I can recall the Section Number, however cannot remember the sub-section or clause at times which forces me to omit writing the section number also. For example the section of Director's Responsibility Statement is Section 139(5). Even if I don't remember the exact Section, can I just write Section 139?? Please kindly guide how to attempt the answer in such cases? Kind Regards