Answer : The correct options is, (C) They conduct an electric current in a solution.
Explanation :
Acid : It is a substance that has ability of donating proton or hydrogen ion, 
.
The properties of an acid are :
- Acids are sour in taste.
- The texture of an acid solution is sticky.
- It changes the color of the litmus paper blue to red.
- It react with a metal to give compound and hydrogen gas.
- They do not conduct an electric current in a solution.
Base : It is a substance that has ability of donating hydroxide ion, 
.
The properties of an base are :
- Base are bitter in taste.
- The texture of an base solution is slippery.
- It changes the color of the litmus paper red to blue.
- It does not react with a metal.
- They conduct an electric current in a solution.
As we know that, a base such as NaOH will dissociate in water to form sodium ion and hydroxide ion. So, the ions of an aqueous solution of base will conduct electricity. That means the base conduct an electric current in a solution.
In acid, the concentration of hydrogen ion is greater than the hydroxide ion but in base the concentration of hydroxide ion is more than the hydrogen ion.
Hence, the correct options is, (C) They conduct an electric current in a solution.
