Which determines what an organism looks like and how it grows and develops?
a. protein
b. cell
c. dna
d. cyclins

Option C, DNA

Explanation:

All the physical characteristics and traits of organisms are related to the alleles present on any gene.  

Some alleles are dominant and hence they express their characteristics while some are recessive allele which may be present in a gene but do not expresses their traits.  

While some time traits are either expressed co-dominantly or independently. DNA carries these genes and hence it plays an essential role in determining the look and way of development of an individual  

Hence, option C is correct

answer; the tunica intima also called tunica interna, consists of elastic fibers,connective tissue and smooth muscle cells;