The correct option is C (b), (a), (c), (d)
Correct sequence : (b) Synapsis → (a) crossing over → (c)Terminalisation of chiasmata → (d) Disappearance of the nucleolus
Synapsis occurs in zygotene and then crossing over in pachytene. Terminalisation occurs in diplotene and finally, the nucleolus disappears in diakinesis.