My brother attends notre dame university. the main clause is?

There is only one clause in this sentence. The entire sentence, in this case, functions as a standalone clause. There isn't a second clause to append to the sentence or to separate the sentences. A clause such as "He first thought he was going to attend Vincennes University, but..." might be considered sufficient to warrant the sentence having two clauses.

The issue of racism greatly inflience herbecause by then there was racio discrimination in the south this affects her such that she will grow up favouring people of her race and undermining the othersracism will build herin earlier days the people of south were oppressed by the whites since they were considered slaves or subject yo the whites.so as a result of this the whites children grew up bearing in mind that they were more superpower than the black