Answer: hello your question is incomplete attached below is the complete question 
answer :
a) 
 ( option D )
 ( option D ) 
b) A = 1/2 (6)(3) ( option B )
c) Area of shaded region = 9 
Explanation:
a) Using integration with respect to x 
 Area = 
 ( note a = 10 )
 ( note a = 10 )
 = y^2/2 - 4y |⁷₄ + 10y - y^2/2 |¹⁰₇
 = 33/2 - 12 + 30 - 51/2 = 9 
hence the best integral from the options attached is option D 

= [ 10x - x^2 /2 - x^2/2 - 9x ] ³₀
= 30 - 9/2 - 9/2 - 12 = 9 
b) Using Geometry 
Area = 1/2 * base * height 
 = 1/2 * 6 * 3 
 = 9