💡 Detailed Explanation
The correct answer is 「つつも」 (tsutsumo), which connects to the Masu-stem of a verb (here 「知りつつも」) and means 'although' or 'despite knowing/feeling...'. It is used when one's actions contradict their thoughts/feelings. 「ながらも」 has a similar meaning but usually attaches to nouns or adjectives. 「ものの」 means 'although' but attaches to plain past forms (e.g. 知っていたものの). 「ついでに」 means 'while/on the occasion of'.