The correct answers are:
B. plant growth;
C. animal actions;
The mechanical weathering is a type of weathering where physical force is included into the breaking up of the rocks. The plants and the animals are both causing this type of weathering with their actions. The plants can cause mechanical weathering with their roots, as they grow and surround a rock, they are able to create such a pressure that they can break the rock apart. Also, as their trunks are getting bigger, if there's rocks right next to them, the pressure from the growing of the trunk will crack the rocks. The animals are able to move the rocks, as well as pushing them, or even deliberately throwing them, so they manage to break up parts of them and cause mechanical weathering.
<h2>Diagonal of circle </h2>
Explanation:
As the skateboarder wants to cross the play ground . The surface is rough .
As we know , the force of friction is non-conservative force . Thus work is required against this force .
We have formula:
work done = Force x distance (in one direction )
Te force applied cannot be changed , so he is to decrease the distance .
In case of circle , diameter is the minimum distance . Thus he is supposed to move along it .
Answer:
Music has an important place in our lives.
Answer:

is time required to heat to boiling point form initial temperature.
Explanation:
Given:
initial temperature of water, 
time taken to vapourize half a liter of water, 
desity of water, 
So, the givne mass of water, 
enthalpy of vaporization of water, 
specific heat of water, 
Amount of heat required to raise the temperature of given water mass to 100°C:



Now the amount of heat required to vaporize 0.5 kg of water:

where:
mass of water vaporized due to boiling


Now the power rating of the boiler:



Now the time required to heat to boiling point form initial temperature:

