Which among the following has the highest resistivity?

Rubber is an insulator that has the highest resistivity.

We know that $R = \frac{\varrho \times L}{A}$; where R is the resistance, ϱ represents the resistivity of conductor while 'L' and 'A' are length and area of cross section of the conductor or wire. 

ϱ is inversely proportional to the conductivity. Rubber has the lowest conductivity hence it has the highest resistivity.