Four wires of equal length and of resistances 10 ohms each are connected in the form of a square. The equivalent resistance between two opposite corners of the square is [NCERT 1977]

• A.                    10 \[ohm\]
• B.                                      40\[ohm\]
• C.                    20\[ohm\]                     
• D.            10/4\[ohm\]