(i) The rectangle has 2 lines of symmetry.

(ii) , This figure has no lines of symmetry.

(iii) In the case of an isosceles triangle. The triangle has one line of symmetry. And for an equilateral triangle, it has 3 lines of symmetry.

(iv) The circle has infinite lines of symmetry.

∴ the figure that is not symmetric with respect to any line is: (ii)

∴ the correct option is B.