The work is to be –– immediately. (১৮তম শিক্ষক নিবন্ধন স্কুল: ২০২৪)

The correct answer is option (b) "done." 'To be + past participle' is a passive infinitive structure used to indicate something that must or should be done. 'The work is to be done' = the work must be completed (obligation/necessity). ✗ 'to be do' — grammatically incorrect. ✗ 'to be doing' = present continuous passive, wrong here. ✗ 'to be did' — incorrect form. Source: English Grammar — Wren & Martin.