However one likes it or not; agriculture will be considered as the primary source of income, even if other manufacturing activities proliferate.
Whether one likes it or not is preferable over however one likes it or not. Thus A and B are out.
A. However one likes it or not; agriculture will be considered as the primary source of income,
This is Incorrect for the reasons stated above.
B. However, one likes it or not agriculture will be considered as the primary source of income
This is Incorrect for the reasons stated above.
C. Whether one likes it or not, agriculture will be considered as the primary source of income,
This is Correct as the comma is needed.
D. Whether one likes it or not agriculture will be considered as the primary source of income,
This is Incorrect for not using comma
E. Whether one likes it or not! agriculture will be considered as the primary source of income,
This is Incorrect for not using comma