Q: You are given a paragraph, with numbered sentences, and a question. Write the numbers of the sentences needed to answer the given question. Separate multiple sentence numbers with a comma (", "). E.g. "1, 2" would be the correct response if Sent 1 and Sent 2 are needed to answer the given question (do not include sentences that contain no information that is necessary to answer the question). Sort the sentence numbers in an increasing order (i.e., '1, 2', instead of '2, 1'). Your answer should not contain anything than the sentence numbers separated by a comma (e.g. '1, 2, 3, 4'). The given question requires more than one sentence to answer. So, your answer must contain at least one comma (", ").
Paragraph- Sent 1: (CNN) -- Federal authorities are investigating threatening letters allegedly containing deadly ricin in Spokane, Washington, the FBI said Thursday.
Sent 2: The FBI and the U.S. Postal Inspection Service are trying to find the source of the two letters, intercepted Tuesday during a screening procedure at a postal facility in Spokane, FBI spokeswoman Ayn Sandalo Dietrich said.
Sent 3: "While we cannot offer further comment on this incident, we stress that law enforcement agencies will continue to assess and address the full spectrum of potential threats," she said.
Sent 4: The American Postal Workers Union was notified of the two suspicious letters by the Postal Service, the union said.
Sent 5: One letter was addressed to the Spokane Post Office and the other to a federal judge in Spokane, the union said.
Sent 6: Both were postmarked May 14, the union said.
Sent 7: Postal Service management told employees they weren't at risk from handling the letters because the suspected substance was not in a form that could be inhaled or readily ingested, the union said.
Sent 8: Preliminary lab tests showed the substance to be ricin, the union said.
Sent 9: The union is monitoring the situation, President Cliff Guffey said.
Sent 10: "Our members' safety is our primary concern," he said in a statement.
Sent 11: In an apparently unrelated case, ricin-tainted letters sent to President Obama and others touched off high anxieties in Washington and elsewhere last month.
Sent 12: James Everett Dutschke, 41, of Tupelo, Mississippi, has been charged with possession and use of a biological agent as a weapon in connection with those letters sent to Obama and others. 
Question: Who is monitoring the situation?.
A:
2, 9.