harder than a GRE logical reasoning question!

Especially the second one,

Question: If Sam started to work for B on 1/3/2011, the Receipt Notice day, for which period Sam belonged to A (or under H-1B sponsored by A)? For which period Sam belonged to B (or under H-1B sponsored by B)?

Please help! my RFE asked me to provide clearly the date of employment under H-1B. I can't figure it out, maybe too old now. Any material for the preparation of this kind of tests?