Spiritualism with its ________ and its so called manifestation of spirits and the like has always seemed to Nehru a rather absurd and ________ way of investigating psychic phenomena and the mysteries of the after life.

The second part of the sentence throws light on Nehru's thought on 'spiritualism with its manifestations of spirits”. Therefore, séances (communicating with) is the most appropriate word to replace the first blank, as all the other options talk of connections. Moreover, 'impertinent' (not pertinent; having no connection with a given matter; irrelevant) is in tandem with absurd. Hence, (4) is the answer.