(a). As the vectors C and D in the given figure are pointing towards the first quadrant of the xy-plane. the angle made by both the vectors with the positive x-axis is small as comapred to the other vectors.
Thus, vector C and D gives the resultant vector with the maximum positive x-component.
Hence, option 4th is the correct answer.
(b). The vector F is aligned towards the positive of the y-axis.
The vector E is at the small angle from the positive of the y-axis.
Other vectors are having either smaller magnitude or directed towards negative of y-axis.
Thus, vector E and F gives the maximum resultant along the positive of y-axis.
Hence, 3rd option is the correct answer.
(c). The vector A and F are opposite in direction. Both are almost align towards the y-axis.
When A and F are subtracted, their magnitude add together.
Thus, A and F is the vector when subtracted gives the maximum value.
Hence, first option is the correct answer.