Answer
The correct option is C.
Reason
Each option is explained with reason which is given below.
Option A
It is incorrect because chromatid is the identical copy of chromosome which is formed during DNA replication. It appears to be an arm of chromosome.
Option B
It is incorrect because paired chromosomes that have genes arranged in the same order are known as homologous chromosomes.
Option C
It is correct option because the part of a chromosome that joins the sister chromatids is known as centromere. It contains a disc shape protein called kinetochore. It is that region where spindle fibers attach during mitosis and is responsible for actual movement of chromosomes during segregation.
Option D
It is incorrect because the material that makes up a chromosome is composed of DNA and proteins. DNA is a polymer of nucleotide monomers. Each nucleotide is composed of:
1. Pentose sugar
2. nitrogenous base, and
3. phosphoric acid
While protein of chromosome is known as histone proteins. The DNA and protein combine to form chromatin a thread like structure which is about 31 cm in human diploid cell. This chromatin is then packed up to make nucleosome. In mammalian cells about 2mm DNA wrapped around eight histone proteins to make a nucleosome unit. The nucleosomes are then packaged up to make chromosome
Conclusion
Thus the correct option is C.
