Alternative correct answer avoiding subjunctive

Question

I think this also translates correctly;Adorno el árbol de Navidad para que todos admirarlo mañana.as an alternative to Adorno el árbol de Navidad para que todos lo admiren mañana.Two correct answers as choices in the original question unless hinted to use subjunctive

Answer

Hola Ian,
Your first sentence would be grammatically incorrect, I am afraid:
Adorno el árbol de Navidad para que todos admirarlo mañana.
When using "para que" you need the subjunctive.
If the sentence were using the same subject, you could have used "para" (without que) followed by the infinitive, like this:
Adornamos el árbol de Navidad para (todos/todos nosotros) admirarlo mañana.
In both clauses the subject is "we". 
But para + que doesn't admit the infinitive, only the subjunctive.
Saludos
Inma