Answer:
R=0.5B+0.5C+2A+D
Explanation:
By the triangular law of vector addition
vector R= vector B- vector D
As A,B,C,D are edges of the parallelogram,
A is parallel to D but opposite in direction.
Therefore
;
;

B is parallel to C and in same direction.



Answer:
C. Photosphere
Explanation:
The lights shown in the figure comes from the outermost layer of the Sun. This layer is called photosphere.
This is the layer from where the light of the Sun is radiated, before travelling through space and reaching us.
The photosphere is the coldest layer of the Sun: its surface temperature is between 4500 and 6000 K. Its width is approximately 100 km.
A characteristic of the photosphere is the presence of the sunspots, which appear as darker spots, and are regions of lower temperature caused by a concentration of magnetic flux.