To start with this issue, it must be said that there are several kinds of injustices, unfortunately in the world.
As I see it, it is pretty difficult to choose the worst injustice.
In general, we feel “the worst injustice” whatever happens in childhood such as: poverty, starvation, diseases or all sort of exploitation.
Another important topic is “equality”.
It is well-known that the true equality doesn’t exist for instance there are racism, xenophobia, homophobia and chauvinism…among others.
Nowadays, it is not known exactly what micro-chauvinism is, but it is so dangerous and relevant than chauvinism, because we do not see it.
We must be very careful with our behaviour in order to vanish this kind of chauvinism.
In addition, there is a bigger injustice such as inequality between developed countries and developing countries.
As you can see, it is so difficult to select just one injustice.
The more aware of injustice we are, the better world we have.