Identify the segment in the sentence, which contains the grammatical error.

Neither Amit nor Raju are staying with his parents in Mumbai.

He was one of those fortunate slave who worked for a humane master,  as a coachman and house servant.

Researchers has developed (1)/ a software system to accurately (2)/ identifies people and cell lines (3)/ from his DNA(4)/ in a matter of minutes (5).

The chairman had not taken(1)/ any decision until(2)/ he had studied(3)/ the case thoroughly.(4)

The research note also highlighted /that in spite the sharp improvement /in economic activity, the key/ services sector is still struggling.

I need a much (A) / highest ladder to (B) / climb on the roof (C)/ and grab all the stuff. (D) / No error (E).

The RBI has judiciously drew up a road-map  which should be good for the country.

The CTC vaccine greatly helped in increasing vaccination coverage in a few areas where excess was a problem and electricity was unreliable.

One of the state (a) / in which there was a severe drought (b) / last year is Maharashtra. (c) / No error (d)