Line insulators are made of Porcelain. The porcelain is aluminium silicate. The aluminium silicate is mixed with plastic kaolin, feldspar and quartz to obtain final hard and glazed-Porcelain insulator material.

Advantages of porcelain insulator :

Very long life, made of inorganic materials and do not age.

Have higher leakage distance profiles.

Easy to identify a damage unit.

Strong in compression.

Hence, the correct option is (A).