A study revealed that, compared with children who do not have autism, most autistic children have underdeveloped motor skills. However, siblings of autistic children do not have any motor impairment.

Based on this excerpt, we can conclude that autism.

b) Is associated with motor impairment but does not cause it

Step-by-step explanation:

The study didn't explain the timeline of their findings, so we can conclude this research takes data at one time. Research that doesn't take before and after exposure data cannot be used to derive causation since we can't prove that the condition happens after the exposure. But this study still can predict association by risk ratio or odds ratio depends on the study design.