The building block of DMA function in larger unites called:

Proteins
Organelles
Genes
Enzymes

DNA is made of chemical building blocks called nucleotides. These building blocks are made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases. To form a strand of DNA, nucleotides are linked into chains, with the phosphate and sugar groups alternating.

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.

plato users:

d.  

there was a variety of food available on island x, but there were only large seeds and nuts on island y.