The correct answer is: Only argument II is strong.
Argument I is a weak argument because it is based on the assumption that students will only be serious about their studies if they have to pay a lot of money. This is not necessarily true. There are many students who are very serious about their studies even though they do not have to pay a lot of money for tuition.
Argument II is a strong argument because it is based on the fact that increasing tuition fees will make it more difficult for meritorious poor students to afford post-graduate education. This is a serious concern, as it means that these students will be less likely to be able to achieve their full potential.
In conclusion, only argument II is strong.