The availability of calcium is highest in which of the following condition? A: The cation exchange capacity is 24 cmol(+)/Kg, while the exchangeable calcium is 12 cmol(+)/Kg B: The cation exchange capacity is 30 cmol(+)/Kg, while the exchangeable calcium is 8 cmol(+)/Kg C: The cation exchange capacity is 8 cmol(+)/Kg, while the exchangeable calcium is 5 cmol(+)/Kg D: The cation exchange capacity is 15 cmol(+)/Kg, while the exchangeable calcium is 6 cmol(+)/Kg

The function of β subunit of polymerase is A: Template binding B: Catalytic binding C: Promoter binding D: Cation binding

Ionic bonding is formed by ( ) A: valence electron transfer‍ B: shared electron pair C: free electron and cation D: attraction of the electric dipoles