Grass tetany in cattle and sheep is due to deficiency

Find the error.

Identify the segment in the sentence that contains a grammatical error.

Many of us are employed and are living in places they are prejudiced to believe is not our home. 

We are concerned about the plight of the normal man.

The most effective measure to keep (1)/ our roads safe is enforcement of rules (2)/ with zero tolerance to any violate rule. (3)/ No error. (4)

Preeti as well as (1)/ her sister are (2)/ going to Pune (3)/  to attend the wedding (4)/ No error (5)

Farmers organisations has (1)/also been complaining about (2)/scarcity of fertilizers and (3)/increase in its price (4).

He has made(A)/ a mistake of(B)/ which I am certain.(C)

Some scientists has argued that Neowise (A)/deserves a “great comet” (B)/designation for its brightness . (C)