They decrease because the zebra mussel were taking their resources. Leaving them nothing to eat.
The right option is; orbital period
T stands for orbital period.
Orbital period is the time a certain astronomical object such as planets takes to complete one orbit (360° revolution) around another object such as sun or stars. Orbital period is expressed in different units of time, usually in years, days or hours.
Of the following given choices;
A. glacial erratics B. U-shaped valleys C. unusually shaped rocks D. mudslides.
The answer is; C.
The wind carries soil particles is it blows. These soil particle hit on rocks in their path and over time gradually erode the rocks. An example of this type of erosion is the aeolian process. Usually the bottom o the rock is eroded more than the top. This is because the bottom is hit by larger soil particles that are heavier to carry by the wind. An example of rock formed in this process is attached in the picture below.
Schizocoely is a process by which some animal embryos develop while splitting the mesodermal embryonic tissue. On the other hand, <span> enterocoelous was formed </span><span>in which the coelom forms from pouches "pinched" off of the digestive tract.</span>