D. A struggle for existence is apparent.
If a struggle for existence is apparent, natural selection occurs because all of the weak/unfit/unadapted ones die.
Answer:
In S phase, the cell synthesizes a complete copy of the DNA in its nucleus. It also duplicates a microtubule-organizing structure called the centrosome.
Explanation:
The following are the environmental factors that can damage genes that code for these enzymes. radiation from sun, various chemicals and x-rays. these agents are referred to as environmental mutagens. they result to changes in the genetic make up of the organism and in turn affect the production of enzymes. enzymes are protein in nature and once the DNA has been compromised their production is affected. in most cases mutated DNA produces enzymes with lost or abnormal function.
C --> He collected a vast amount of data and observations that fueled later theories
