JNU SSS 2011 Question 93: Logic and proof techniques

There are four candidates for an award—$A$, $B$, $C$ and $D$ Only one of the four candidates had cleared both Tests I and II. Only one candidate had cleared both Tests I and III. Only one candidate had cleared both Tests I and IV. Only one candidate had cleared both Tests II and III. Only one candidate had cleared both Tests II and IV. Only one candidate had cleared both Tests III and IV. Both $A$ and $B$ had cleared Test I. Both $C$ and $D$ had cleared Test II. Both $B$ and $C$ had cleared Test III. $D$ had cleared Test IV. The award went to the candidate who had cleared more tests than any other candidate. The award was given to