The correct answer is 3. The blank is succeeded by the conjunction ‘and’ and the word is ‘nescience’. This means that a word which has a similar meaning to the word ‘nescience’ must be used. 'Nescience' means 'the lack of knowledge or ignorance'. Both 'ignorance' and 'unawareness' are synonyms of the word 'nescience'. Let us look at the meaning of the other words. Omniscience- the state of knowing everything Obstinacy- Stubbornness Obstetrics- the branch of medicine and surgery concerned with childbirth and the care of women giving birth Platitude- a remark with a moral content