Sentence 1: I retired from my job in September of 2012. 
 Sentence 3: I was a trolley and subway car fan 
 Sentence 4:  Last week an ex coworker sent me a marketing item issued by the MBTA 
 Sentence 5:  I emailed her my thanks 
 Option 1: I worked for petco, a pet store. 
 Option 2: I worked for the MBTA, a mass transit authority.