google.com, pub-5240966689518563, DIRECT, f08c47fec0942fa0

Given that electronegativity increases across a period and decreases down a group in the periodic table, in which of the following compounds will the molecules be held together by the strongest hydrogen bond?
A. HF(g)
B. NH3(g)
C. CH4(g)
D. HCl(g)