the logic is this: the company is planning to launch the same concept for housewares coz it worked for clothing catlaog.
After implementing the concept in clothing, the company saw a jump in its sale. The reason is attributed to upscale clientele.

The question asks us to find the assumption- what works for clothing catalog by appeal works for housewares too.

Lets look at options:

(A) other housewares catalogs with magazine like formats do not already exist [ we are not bothered about other houseware catalogs. we are only concerned about this company and this concept. Eliminated]

(B) an upscale clientele would be interested in a housewares catalog [ states our assumption perfectly. My answer]

(C) the same copywriter and graphic artist could be employed for both the clothing and housewares catalogs [are we bothered about the same ppl involved? we are concerned if this concept would work magic the same way it did for clothing catalog. eliminated!]

(D) a magazine like format requires a copywriter and a graphic artist [ we are not bothered about the ppl involved or what it involves. we are concerned about the net result. Eliminated!]

(E) customers to whom the old clothing catalog appealed would continue to make purchases from catalogs with the new format [whether they continue to purchase or not is not the deal here. even if they didnt purchase, still the clothing catalog saw an increase in its sales. we just need to see if such an increase occurs in the housewares concept too. Eliminated! ]

Hope this helps!

I was down to B and E but the answer is clearly B

Whether the mag appeals to its clothing customer segment is not relevant to the argument.

B

Clearly, it assumes that UPSCALE clientele would be interested in houseware as much as in fashion...