d
\(CH\equiv CH\) \(\overset{H{{g}^{++}}}{\mathop{\xrightarrow[{{H}_{2}}{{O}^{+}}]{}}}\,\,\underset{(B)}{\mathop{C{{H}_{3}}\,-\,\,CHO}}\,\,\,\underset{{{H}_{2}}O}{\mathop{\xrightarrow{C{{H}_{3}}-\,Mg\,-\,x}}}\,\,\,\)\(C{{H}_{3}}\,-\,\underset{(C)}{\mathop{CH\,-}}\,\,(OH)C{{H}_{3}}\,\xrightarrow{(O)}\,C{{H}_{3}}\,-\,\underset{(D)}{\mathop{C}}\,OC{{H}_{3}}\)