1 can not be correct , substring of regular is not always regular
for example L1=0m1n which is regular
a substring of it is 0a1a where a<m,n it is CFL
so looks like D is the answer
III is correct as recursives are closed under complementation!
i do not know how II is correct ,coz lets we have a cfl=0m1m 0n1n where m<n
now a substring 0m1m0m is substring but it is not CFL..it is CSL
so only III should be correct