The correct answer is Of course, some will say that
Step-by-step explanation:
Counterclaims show a different point of view that the one supported by the author; due to this, it is common the counterclaim is linked by using transitions such as however, others believe, many people argue, another point of view is. In this context, the best transition to complete the text is "of course, some will say that" because the section "some will say" directly states this position is different from the one of the author. Also, this is the only transition that represents contrast, which is necessary to let the reader know this position is opposite and due to this, it is rebutted by the author.