I'm almost 100% it is the first option
Secondary succession happens more often because it occurs after some kind of distribution that still leaves the soil intact (mudslide,bulldozing,shoveling,or scraping off an area)
Answer:
I feel it's to easily differentiate the positive from the negative...... like in gram staining of bacteria, the colour tell us which bacteria is gram positive or gram negative...... I just feel that this is science and it is advisable to know what the opposite result of an experiment should look like.
Answer:
The pitch of a sound is how high or low a sound is when we hear it, whereas the intensity of a sound is the energy/vibrancy of the sound over an area and depends on the frequency of the sound as well.