Ka2 of Maleic acid is lesser than Ka2 of fumaric acid due to :
a. intramolecular hydrogen bonding in the formed after one proton removal in fumaric acid
b. intermolecular hydrogen bonding in the ion formed after one proton removal in maleic acid
c. intramolecular hydrogen bonding in the ion formed after one proton removal in maleic acid
d. intermolecular hydrogen bonding in the ion formed after one proton removal in fumaric acid