Task: Please answer the multiple choice question.
Question: Which molecule has the longest half life in humans after IV administration?
Constraint: Even if you are uncertain, you must pick either a or b without using any other words.
Options:
[a] O=NN(CCCl)C(=O)NCCCl
[b] CCC(=O)O[C@]1(C(=O)SCF)[C@H](C)C[C@H]2[C@@H]3C[C@H](F)C4=CC(=O)C=C[C@]4(C)[C@@]3(F)[C@@H](O)C[C@@]21C
Answer: a
Task: Please answer the multiple choice question.
Question: Which molecule has the longest {half_life_duration__names__noun}?
Constraint: Even if you are {#uncertain|not sure!}, you must pick either {%multiple_choice_enum%2-5%aA1} without using any {#other|additional!} words.
Options:
{SMILES%half_life_duration%}
Answer: {%multiple_choice_result}
1,3-bis(2-chloroethyl)-1-nitrosourea