Requirement for wire-bound standard resistors

A standard resistor should have resistance as constant as possible with temperature.

Since $R = \rho \frac{L}{A},$ for a given wire, $L$ and $A$ are fixed, so resistance mainly depends on resistivity $\rho$.

Therefore, for a standard resistor, we want a material whose resistivity changes very little with temperature.

Desired $\rho$ vs $T$ graph

That means the best graph is the one where $\rho$ is almost independent of temperature, i.e. the curve is nearly horizontal.

Physical reasoning

Materials used for standard resistors (such as manganin, constantan) are chosen because they have a very small temperature coefficient of resistivity.

So their $\rho$ vs $T$ curve is approximately a straight line with very small slope, or nearly flat.

Choosing the correct option

Hence, the suitable curve is the one corresponding to minimum variation of resistivity with temperature.

That is Option D.

Comparison with stored answer

Derived answer: D
Stored correct answer: D

So, the answers agree.