Its simple:
here AB is candidate key.
for R it is not in BCNF AND 3NF for sure.
to check for 2NF, we are not able to find any partial dependency, hence according to the definition of 2NF, if there is no partial dependency then R is in 2NF.
Also for ADE->F, there is no partial dependency(means not any part of candidate key is pointing to non primary attribute). ADE will be treated as one single variable. EX- A->F is partial as A is part of candidate key AB but not ADE->F as ADE whole is not part of candidate key AB
Also S is in BCNF
to check AB->C , here AB is super key hence BCNF