What is the difference between a chromatid and a chromosome?

a. chromatids consist of dna, whereas chromosomes consist of proteins.

b. chromosomes are always replicated, whereas chromatids are not.

c. a chromatid always consists of two linear dna molecules, whereas a chromosome always consists of just one linear dna molecule.

d. a chromatid is one half of a replicated chromosome, whereas a chromosome consists of dna wrapped around proteins in a highly organized manner?