23 C because only Pentan-3-ol has a chiral carbon. Drawing the displayed formula for such type of questions REALLY helps
30 Na will react with an alcohol to give R-O Na , the number of oxygens remains the same. Elimination will occur with Al2O3, with option B esterification will occur with the acid which increases the number of oxygen atoms and in option C OH group will be replaced by HBr. So D is the answer