Quantum of Solace

James Bond is driving from Lake Garda to Siena, Italy, with the captured Mr. White (Jesper Christensen) in the boot of his car. After evading pursuers, Bond delivers White to M, who interrogates him regarding his organisation, Quantum. M's bodyguard, Craig Mitchell (Glenn Foster), is a double agent; he attacks M, enabling White to escape. Bond chases Mitchell and kills him. Bond and M return to London and search Mitchell's flat, discovering that Mitchell had a contact in Haiti, Edmund Slate (Neil Jackson). Bond learns that Slate is a hitman sent to kill Camille Montes (Olga Kurylenko) at the behest of her lover, environmentalist entrepreneur Dominic Greene (Mathieu Amalric). Observing her subsequent meeting with Greene, Bond learns that Greene is helping exiled Bolivian General Medrano (Joaquin Cosio)âwho murdered Camille's familyâto overthrow his government and become the new president, in exchange for a seemingly barren piece of desert.
After rescuing Camille from Medrano, Bond follows Greene to a performance of Tosca in Bregenz, Austria. Meanwhile, the head of the CIA's South American section, Gregg Beam (David Harbour), strikes a noninterference deal with Greene for access to putative stocks of Bolivian oil. Bond infiltrates Quantum's meeting at the opera, identifying members of Quantum's executive board, and a gunfight ensues. A Special Branch bodyguard working for Quantum member Guy Haines (Paul Ritter), is killed after he fights with Bond. M assumes that Bond killed him, and has Bond's passports and credit cards revoked. Bond heads to Italy and convinces his old ally RenÃ© Mathis (Giancarlo Giannini) to accompany him to Bolivia. They are greeted by Strawberry Fields (Gemma Arterton), a consular employee who demands that Bond return to the UK immediately. Bond seduces her and they attend a fundraising party Greene holds that night. At the party, Bond again rescues Camille from Greene. Leaving, Bond and Camille are pulled over by Bolivian police working for Medrano. They had earlier attacked Mathis and put him in the boot of Bond's car to frame Bond. In the ensuing struggle, Mathis is killed.
The following day, Bond and Camille survey Quantum's intended land acquisition by air; their plane is shot down by a Bolivian fighter aircraft. They skydive into a sinkhole, and discover that Quantum is damming Bolivia's supply of fresh water to create a monopoly. Back in La Paz, Bond meets M and learns that Quantum murdered Fields by drowning her in crude oil. Bond meets CIA Agent Felix Leiter (Jeffrey Wright), who discloses that Greene and Medrano will meet in the Atacama Desert to finalise their agreement. Warned by Leiter, he evades the CIA's Special Activities Division when they attempt to kill him.
At an eco hotel in the desert, Greene tells Medrano that now he controls the majority of Bolivia's water supply, Medrano must accept a new contract that makes Greene Planet Bolivia's sole water utility company at significantly higher rates. Bond infiltrates the hotel, kills the chief of police (Fernando GuillÃ©n Cuervo) for betraying Mathis, and confronts Greene. Meanwhile, Camille kills Medrano, avenging the murders of her family. The struggle leaves the hotel destroyed by fire. Bond captures Greene and interrogates him about Quantum, leaving him stranded in the desert with only a can of engine oil.
Bond travels to Kazan, Russia, where he finds Vesper Lynd's former lover, Yusef Kabira (Simon Kassianides), a member of Quantum who seduces women with valuable connections, and who is indirectly responsible for her death. Bond tells Kabira's latest target, Corrine Veneau (Stana Katic), a Canadian Intelligence agent, of his true intentions, thus sparing her Vesper's fate. He allows MI6 to arrest Kabira. Outside, M tells Bond that Greene was found dead in the middle of the desert, shot twice and with engine oil in his stomach. M tells Bond that she needs him back; he responds that he never left. Walking away, he drops Vesper's necklace in the snow.

Question: Who who interrogates Mr. White regarding his organisation, Quantum?
Answer: M.