Final answer:
The best translation is 'Para asistir a la universidad, necesitas sacar buenas notas.'
Step-by-step explanation:
The best translation for the English sentence 'In order to attend college, you need to get good grades' is Para asistir a la universidad, necesitas sacar buenas notas. The use of 'Para' in this sentence indicates the purpose or goal (in this case, attending college) for which an action (getting good grades) is necessary.
'Por' is not suitable in this context because it usually indicates a cause or reason rather than a purpose. For example, 'Por asistir a la universidad, necesitas obtener una beca' (For attending college, you need to get a scholarship).
Therefore, 'Para' is the correct choice in this case.
Learn more about Choosing between por and para in Spanish