The quantity of x-rays or gamma rays required to produce a given amount of ionization in a unit mass of air defines the

Which of the following describes thin radiolucent lines of fairly uniform width that sometimes exhibit radiopaque borders and are commonly found on mandibular anterior intraoral radiographs?

A) Enamel B) Lamina dura C) Nutrient canals D) Genial tubercles

Also known as Lou Gehrig's disease, ____ is a degenerative disease of the spinal cord and brain. 

A. Alzheimer's disease B. amyotrophic lateral sclerosis C. multiple sclerosis D. epilepsy E. meningitis