Ageologist finds a mineral sample along side a swift flowing river determines that the middle is a type of courts which statement is true about this mineral

Where is the

Their are less so maybe the bathroom

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.