The solution set of the inequation $3x + 5y < 7$ is : (a) whole $xy$-plane except the points lying on the line $3x + 5y = 7$. (b) whole $xy$-plane along with the points lying on the line $3x + 5y = 7$. (c) open half plane containing the origin except the points of line $3x + 5y = 7$. (d) open half plane not containing the origin.