A College Student Decides to Enter the Peace Corps After $\degree$

A college student decides to enter the Peace Corps after graduation and is assigned to teach English in sub-Saharan Africa,where the ambient temperature averages 100 $\degree$ F.During the first few weeks of his stay,he notes copious sweating and mild constipation.His gastrointestinal symptoms are probably due in part to upregulated expression of which of the following transport proteins?

A) Cystic fibrosis transmembrane conductance regulator (CFTR)
B) Electrogenic Na⁺/HCO₃^- cotransporter 1 (NBC1)
C) Apical sodium-dependent bile acid transporter (ABST)
D) Na⁺/K⁺/2Cl^- cotransporter,isoform 1 (NKCC1)
E) Epithelial sodium channel (ENaC)