White blood cells (D) aid in the immune system to fight infections.
The scientific method<span> is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. To be termed </span>scientific<span>, a </span>method<span> of inquiry is commonly based on empirical or measurable evidence subject to specific principles of reasoning.</span>
Adaptation is a response to the environment but long term.
For example:
A wolf has a fur coat as an adaptation to the cold weather, but birds migrating south is a response to cold weather.
Answer:
That is a nucleotide which is the monomer of a nucleic acid
Explanation:
