Cell division vocabulary .

Chromosomes-a threadlike structure of nucleic acids and protein found in the nucleus of most living cells, carrying genetic information in the form of genes.  

Chromatin-the material of which the chromosomes of organisms other than bacteria are composed. It consists of protein, RNA, and DNA.

Chromatid-each of the two threadlike strands into which a chromosome divides longitudinally during cell division. Each contains a double helix of DNA.

Centromere-the region of a chromosome to which the microtubules of the spindle attach, via the kinetochore, during cell division.

Centriole- a minute cylindrical organelle near the nucleus in animal cells, occurring in pairs and involved in the development of spindle fibers in cell division.

Explanation:

i think a) betsy can donate only blood to mark is correct because, mark and betsy have the same blood type. whereas nobody else has b+ blood so betsy can't donate to them.