Which of the Following Will Result in Changing the Orientation

Which of the following will result in changing the orientation of bonds between carbon and other atoms from a tetrahedral configuration to a planar configuration?

A) the presence of single covalent bonds with oxygen atoms
B) the presence of single covalent bonds with nitrogen atoms
C) the presence of double covalent bonds between the carbon atom and other atoms
D) the presence of polar covalent bonds between carbon and other atoms