Why Was the Use of the Sweat Gland CDNA Library

Multiple Choice

Why was the use of the sweat gland cDNA library critical in identifying the CF gene?
1) The CF gene is only expressed in epithelial cells of the lungs,pancreas,salivary glands,sweat glands,intestine,and reproductive tract
2) The CF gene is not expressed in any other tissue than sweat glands
3) The CF gene is not expressed in sweat glands

A) 1
B) 2
C) 3
D) 1 and 2
E) All of these