errors?

The aim of this question is to know if it's possible to use simple present in the reported speech?

Yes, it is.

so is the previous sentence correct?

Yes. For example, The teacher said, " The world is round."

In reported speech, The teacher said that the world is round. 0R

The teacher said that the world was round. ("was" is used because the verb "said" is past tense.)

Note: In an exam, use the first answer.

tamguatlayYes. For example, The teacher said, " The world is round."In reported speech, The teacher said that the world is round. 0RThe teacher said that the world was round. ("was" is used because the verb "said" is past tense.)Note: In an exam, use the first answer.

Does that mean that it's possible to use the simple present when talking about someone's beha

In examples like this, whether the context is past or present, when something is still true, we need the present tense.
My grandfather told me once when I was nine that we have 4 seasons because the earth is tilted at 23.5 in respect to its orbit.

These are fine:

I just told my dad that he's very rude to me.
I just told my dad that he's been very rude to me.

AnonymousIn examples like this, whether the context is past or present, when something is still true, we need the present tense.My grandfather told me once when I was nine that we have 4 seasons because the earth is tilted at 23.5 in respect to its orbit.

Your version is correct, but this is possible:

My grandfather told me once when I was nine tha