What does the word argued in the third paragraph mean?

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions.
Last week I went to visit Atlantic College, an excellent private college in Wales. Unusually, it gives people much needed experience of life outside the classroom, as well as the opportunity to study for their exams. The students, who are aged between 16 and 18 and come from all over the word, spend the morning studying. In the afternoon, they go out and do a really useful activity, such as helping on the farm, looking after people with learning difficulties, or checking for pollution in rivers.
One of the great things about Atlantic College students is that they come from many different social backgrounds and countries. As few can afford the fees of £20,000 over two years, grants are available. A quarter of students are British, and many of those can only attend because they receive government help.
“I really admire the college for trying to encourage international understanding among young people", as Barbara Molenkamp, a student from the Netherlands, said. "You learn to live with people and respect them, even the ones you don't like. During the summer holidays, my mother could not believe how much less I argued with my sister."
To sum up, Atlantic College gives its students an excellent education, using methods which really seem to work.