If x1,x2,x3,x4x_1, x_2, x_3, x_4x1,x2,x3,x4 are in arithmetic progression, then which value is equal to x1+x4x_1 + x_4x1+x4?
x2+x3x_2 + x_3x2+x3
2x22x_22x2
x1+x2x_1 + x_2x1+x2
x3−x2+x1x_3 - x_2 + x_1x3−x2+x1