💡 Detailed Explanation
The phrase '～ものだから' is used to state a personal reason, often as an excuse or justification. It explains that the speaker forgot the documents because of the personal reason of 'being in a hurry,' conveying a sense of apology. The other options do not fit the context. 'おかげで' is used for positive results, 'からには' for determination or obligation, and 'せいか' for an uncertain cause.