Which of the following order is correct for the indicated property?

 For the electropositive charracter , the correct  order is $\mathrm{Na}>\mathrm{Mg}>\mathrm{Cu}$

Sodium  lose electrons relatively quickly due to low ionization energy. As a result, they can be described as strongly electropositive. As we descend the group from Cu to Na, the electropositive property gets stronger.

They let off electrons when exposed to light because they have a strong electropositive character. The phrase “photo-electric effect” is used to describe this phenomenon. Photoelectric cells extensively utilize these components.

Sodium is employed much more in photoelectric cells than other alkali metals, since it is extremely electropositive compared to other elements.

Hence, the correct order is: $\mathrm{Na}>\mathrm{Mg}>\mathrm{Cu}\text{ (Electropositive character) }$