A bar of platinum was once used to represent the exact mass of what?

Here is the question :

A BAR OF PLATINUM WAS ONCE USED TO REPRESENT THE EXACT MASS OF WHAT?

Here is the option for the question :

1 ounce
1 kilogram
1 gram
1 pound

The Answer:

And, the answer for the the question is :

1 kilogram

Explanation:

[STC008819]. Between the years 1889 and 2019, the exact mass of one kilogram was standardized across the globe using a bar of platinum. Planck’s constant, a universal formula that may be found in the laws of physics, was substituted for the bar, which became known as “Le Grand K.” Although the first bar of platinum was cast in England, it was stored in a vault that was temperature and humidity controlled just outside of Saint-Cloud, France.