What causes variations in a species

What do scientists need to look at before developing an argument

Which part of the spine is likely to cause a nerve signal to travel faster? a. backbones b. white matter c. nuclei d. gray matter

Select all the correct answers. for a claim about the natural world to be considered scientific, what attributes must it have? a). it must be open to modification if new evidence doesn't completely support it. b). it must be based on scientific observations that can be repeated in a controlled setting. c). it must be applicable to future events and occurrences. d). it must be consistent with only a small portion of relevant observations or data.