A thin rod extends from (x=0) to (x=L). It carries a non-uniform mass per unit length (μ = Mxa/La), where (M) is a constant with units of mass, and (a) is a non-negative dimensionless constant. Find the total mass of the rod. 
a) (Ma+1/aL) 
b) (ML) 
c) (M) 
d) (Ma-1/aL)