The correct statement is: Chromosomes are made up of genes.
To clarify the other statements:
- Chromatids are the two identical halves of a duplicated chromosome, so they contain portions of the same chromosome, not separate chromosomes.
- Genes do not encode deoxyribonucleic acid (DNA); rather, genes are segments of DNA that code for proteins or RNA molecules.
- Centromeres do not connect two chromosomes; they connect two sister chromatids of a single chromosome.