Fundamentally, all human beings possess a combination offixed inherited traits. All individuals possess the .............(1) highly developed nervous system, backbones, erect posture, hair,etc. Therefore, ...........(2) among human beingsarise only in ..............(3) changesofthis basic pattern. Racial differences ..............(4) one of the finest distinctions and are based only on ..........(5) slight differences.
Select the most appropriate option that will fill in the blank number 5.

Options

A. hidden
B. possible
C. clear
D. certain

Answer

D