b
\((b)\) \(\underset{1.20\,\overset{o}{\mathop{A}}\,}{\mathop{{{C}_{2}}{{H}_{2}}}}\,<\underset{1.34\,\overset{o}{\mathop{A}}\,}{\mathop{{{C}_{2}}{{H}_{4}}}}\,<\underset{1.39\,\overset{o}{\mathop{A}}\,}{\mathop{{{C}_{6}}{{H}_{6}}}}\,<\underset{1.54\,\overset{o}{\mathop{A}}\,}{\mathop{{{C}_{2}}{{H}_{6}}}}\,\)