What does the speaker mean when she says there was "foreign dirt still on our soles"?

Which sentence is an example of an i-statement? a) this is by far the worst report you have ever submitted b) your report has so many mistakes that we can’t use it c) i am unhappy to learn that you overlooked crucial details in the report. we just lost a potential client d) i guess the person who wrote this repost didn’t understand the consequences of submitting poor quality work