How Is the Burden of a Tax Divided

How is the burden of a tax divided?
i) When the tax is levied on the sellers, the sellers bear a higher proportion of the tax burden.
Ii) When the tax is levied on the buyers, the buyers bear a higher proportion of the tax burden.
Iii) Regardless of whether the tax is levied on the buyers or the sellers, the buyers and sellers bear an equal proportion of the tax burden.
Iv) Regardless of whether the tax is levied on the buyers or the sellers, the buyers and sellers bear some proportion of the tax burden.

A) i) and ii) only
B) iv) only
C) i) , ii) , and iii) only
D) i) , ii) , and iv) only