For Q 7 - The correct ans choice is (D), however I'm unable to eliminate ans choice (E).
a) Ans (E) begins with "Historical dispute" - the statement in para 1 "Custom.....more humane society...........economic rather than humanitarian" is evident of the dispute. Since some view ransoming as a humanitarian step, which means others (including the author) view it as an economic step.
b) Ans (E) second part mentions "One side is examined in detail" - Which I feel is true since the entire passage examines "procedures to reduce transaction costs".