Final answer:
The phrase "of or how comfortable are" in the sentence should be corrected to "or how comfortable is."
Step-by-step explanation:
The phrase "of or how comfortable are" in the sentence can be corrected as "or how comfortable is".
The sentence should read as: "A recent magazine ad for women's clothing makes no reference to the quality of or how comfortable is the company's clothes."
In this correction, the verb "are" is changed to "is" to match the singular noun "comfortable."
Learn more about Correcting grammar in a sentence