The Han Chinese ethnicity, known within China as the "Descendants of the Yan and Huang Emperors",
constitute 92% of the People's Republic of China and 20% of the human population, making them the largest single ethnic group in the world.
BY POE
A.
constitute 92% of the People's Republic of China and 20% of the human population, making
them--> Both 'constitute' and 'them' suggest 'Han Chinese ethnicity' plural, which is incorrect: SV error.
B.
constitutes 92% of the People's Republic of China and 20% of the human population, and consequently
it is--> Corrects SV error
C.
make up the constituents of 92% of the People's Republic of China and 20% of the human population, and make
them--> Same as A
D.
are the constituents of 92% of the People's Republic of China and 20% of the human population, and therefore
is making
it--> Here apart from SV error (are), the usage of 'is' means 'the constituents' are making 'Han ethnicity' largest. Meaning issue.
E.
have been constituting 92% of the People's Republic of China and 20% of the human population, and have made
them--> Here apart from SV error (have been + them), present continuous (have +been constituting) means that constituting is a process and it started sometime in the past and continues till date. Meaning issue.