Lisa Has Been Widowed Three Times

Lisa has been widowed three times.Her first husband died in 2009 leaving an unused exclusion amount of $3.5 million.The second husband died in early 2011 leaving the entire $5 million exclusion amount unused.Lisa's third husband died in late 2011 with an unused exclusion amount of $4 million.Lisa's DSUEA is:

A) $3.5 million.
B) $4 million.
C) $5 million.
D) $9 million.
E) $12.5 million.