Hi there my friend :)
Your answer is C. frequency
Hope this helps :)
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The displacement distance from my house to school never changes but the time it takes varies due to traffic and it's effects on my vehicle's speed and position in line at stop lights.
Unlike fixed joints or cartilaginous joints, where the bones are connected by either connective tissue or cartilage, the bones in synovial joints are not directly joined by anything, which allows for a much greater range of motion.