The following is the test-tube contaning DNA from Meeselson and Stahl experiment. Find out what a,b and c could be:

Question

( a ) b-$N_{14}-N_{14},c-N_{14}-N_{15}, a-N_{15}-N_{15}$
( b ) a-$N_{14}-N_{14},b-N_{14}-N_{15}, c-N_{15}-N_{15}$
( c ) b-$N_{14}-N_{14},a-N_{14}-N_{15}, c-N_{15}-N_{15}$
( d ) c-$N_{14}-N_{14},b-N_{14}-N_{15}, a-N_{15}-N_{15}$