<span>Educational Requirements. Training to become an ultrasound technician can be done through a formal education program or through military training. The most common training is an associate's degree program, although there are bachelor's degree and 1-year certificate programs available.</span>
Answer:
A. Sound waves can travel through and reflect off rock layers.
Explanation:
Reflection seismology is a process of "seeing" below the ground using artificial sources to create sound waves or the process of learning about rock layers beneath the surface of Earth using sound waves.
Sources on land, uses vibration trucks to shake the ground very powerfully to produce sound waves.
Thus, the sound waves will travel through the earth and reflect off rock layers having different acoustic properties. In order to record this reflections, we make use of a small instrument called geophones.
Last one: Every object in the universe attracts every other object