In the sentence identify the segment which contains the grammatical error. Friction reduce the effieciency of machines so their value also gets reduced.

Options

A. the efficiency of machines
B. so their value
C. Friction reduce
D. also gets reduced.

Answer

C

Explanation

Friction reduce will be replaced by Friction reduces.
Singular Subject `to` Singular Verb with s
Plural Subject `to` Plural Verb with-out s
Friction `to` Singular Subject