The correct answer is option 3: the human body. An electric conductor is a material that allows the flow of electric current through it.

Option 1, a plastic sheet, is not an electric conductor because plastic is an insulator. Insulators do not allow electric current to flow through them easily.

Option 2, distilled water, is also not an electric conductor. Although water in its pure form is not a good conductor, it can become conductive when impurities or dissolved substances are present. However, distilled water is purified and does not contain these impurities, making it a poor conductor.

Option 4, a wooden thin sheet, is also not an electric conductor. Wood is an insulator and does not allow electric current to flow through it easily.

Option 3, the human body, is an electric conductor. The human body contains electrolytes, such as salts and water, which enable the flow of electric current. This is why humans can feel electric shocks and why medical devices like EKGs and defibrillators work by transmitting electric signals through the body.