The correct answer is a,b and c.
a) its core becomes a white dwarf.
b) its outer layers form a nebula , or vast cloud of gas and dust.
c)its outer layers expand , and the star becomes a red giant.
Tsunami can also occur form earthquakes
<u>Answer:</u>
<em>Anytime observations need to be clarified. When an unusual condition need to be shown for later reference.</em>
<u>Explanation:</u>
Instead of just recording the data the is sometimes important to be sketched out as the data observed is needed to be clarified and also sometimes there is an unusual condition that occurs and hence, it is important to sketch it so that it can be used for later reference.
<em>Therefore, when we are aware of the situation we need not sketch the data.</em>
