(i) Area enclosed by two concentric circles with radius R and r respectively such that R > r is π(R2 – r2).(ii) The length of tangents drawn from an external point to a circle are not equal.(iii) There is one and only one tangent at any point on the circumference of a circle.(iv) Ratio of the area of the sector of a circle with central angle 90° to the area of that circle is 1 : 4.A (i)-F, (ii)-F, (iii)-F, (iv)-F B (i)-F, (ii)-T, (iii)-F, (iv)-F C (i)-T, (ii)-F, (iii)-T, (iv)-T D (i)-T, (ii)-T, (iii)-T, (iv)-T

The correct answer is C.

(i) The area enclosed by two concentric circles with radius R and r respectively such that R > r is indeed π(R2 – r2). This is because the area of a circle is given by πr^2, so the area between two concentric circles is the difference of their areas, which is πR^2 - πr^2 = π(R2 – r2).

(ii) The statement that the length of tangents drawn from an external point to a circle are not equal is false. In fact, the lengths of the tangents drawn from an external point to a circle are always equal. This is a well-known property of circles.

(iii) There is indeed one and only one tangent at any point on the circumference of a circle. This is a fundamental property of circles.

(iv) The ratio of the area of the sector of a circle with central angle 90° to the area of that circle is indeed 1 : 4. This is because a sector with a central angle of 90° represents 1/4th of the total area of the circle, since 90° is 1/4th of 360°.