Lou dies on April 12, 2007. All of Lous property passed to Paula, his daughter. Paula dies

Question:

Lou dies on April 12, 2007. All of Lou’s property passed to Paula, his daughter. Paula dies January 15, 2009. Both Lou’s and Paula’s estates pay federal estate taxes. Lou’s estate tax was $350,000. How much can Paula’s estate claim for a credit for tax on prior transfers?
a. $350,000b. $280,000c. $210,000d. $140,000