As the elements in period 2 are considered from left to right.

Iwould tell u but its against rules

To inform the reader

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.

Its probably the possible factors tt, tt, tt,