What are the three types of rocks that are part of the rock cycle? A Hard, soft, and Brittle correct answer
B Sand, stone, and volcanic correct answer
C Dactylic, iambic, and Spondaic correct answer
D Igneous, metamorphic, and sedimentary

D. Per National Geographic

There are three main types of rocks: sedimentary, igneous, and metamorphic.

Which of the following is an example of an opposing signal? no examplthates given.   i would say, that traffic lights in a city at major intersections direct the flow of traffic in opposite directions so would be an example.also, stop signs on either side of the same street would be an example. at a train crossing, the light for allowing car traffic in opposite directions or not would be another example.