Question: Jeff Bauman Jr. lost his legs at what terrorist attack on April 15, 2013, near the finish line?

Context paragraphs:
Sack race: The sack race or gunny sack race is a competitive game in which participants place both of their legs inside a sack or pillow case that reaches their waist or neck and hop forward from a starting point toward a finish line.  The first person to cross the finish line is the winner of the race.

Stronger (film): Stronger is a 2017 American biographical drama film directed by David Gordon Green and written by John Pollono, based on the memoir of the same name by Jeff Bauman and Bret Witter.  It follows Bauman, who loses his legs in the Boston Marathon bombing and must adjust to his new life, and stars Jake Gyllenhaal as Bauman, with Tatiana Maslany, Miranda Richardson, and Clancy Brown in supporting roles.

Adriana Pirtea: Adriana Nelson, née Pirtea (born January 31, 1980) is a Romanian American long-distance runner who made her marathon debut in the Chicago Marathon held on October 7, 2007, with a second-place finish.  She led by a few dozen meters in the final 300 meter stretch run down Columbus Drive on a day of record-setting 88 °F temperatures, but she was caught just before the tape by the defending Chicago Marathon women's champion, Berhane Adere.  Pirtea had held a 30-second lead with 600 meters remaining but never looked back as Adere slipped down the right side of the final straightaway under the shield of male runners.  Adere was so far to the right that as she crossed the finish line she did not take the tape which was being held at the left side of the finish line.  The 2007 Chicago Marathon was the slowest women's Chicago finish since 1992 due to the heat.  Pirtea had been a pacemaker at the January 28, 2007, running of the Osaka Ladies Marathon, and an injury prevented her from making her marathon debut at the London Marathon on April 22, 2007.

Boston Marathon bombing: On April 15, 2013, two homemade bombs detonated 12 seconds and 210 yd apart at 2:49 p.m., near the finish line of the annual Boston Marathon, killing three people and injuring several hundred others, including 16 who lost limbs.

Racing flags: Racing flags are traditionally used in auto racing and similar motorsports to indicate track condition and to communicate important messages to drivers.  Typically, the starter, sometimes the grand marshal of a race, waves the flags atop a flag stand near the start/finish line.  Track marshals are also stationed at observation posts along the race track in order to communicate both local and course-wide conditions to drivers.  Alternatively, some race tracks employ lights to supplement the primary flag at the start/finish line.

2000 terrorist attack on Red Fort: On 22 December 2000, a terrorist attack took place on Red Fort in Delhi, India.  It was carried out by Pakistani terrorist group Lashkar-e-Toiba.  It killed two soldiers and one civilian, in what was described in the media as an attempt to derail the India-Pakistan peace talks.  Red Fort is an extremely important Indian facility as it hosts the Prime Minister of India annually on August 15.  The Red Fort is also significant historically as it was taken over from British control and is an iconic site in India.  As a result of the attack, the Indian capital of Delhi, and India as a whole was shaken from the incident.

PNS Mehran attack: The PNS Mehran attack was an attack/shooting by Tehrik-i-Taliban Pakistan (TTP) and Al Qaeda which took place on 22 May 2011, at PNS Mehran, the headquarters of the Pakistan Navy's Naval Air Arm and the most populous Pakistani military installation.  It is located near the PAF's Faisal Air Force Base of Karachi, Sindh.  In the course of the event, 15 attackers killed 18 military personnel and wounded 16 in a sophisticated terrorist attack.  Two American-built P-3C Orion surveillance aircraft were destroyed.

Thomas Preston Davis: Dr. Thomas Preston Davis, MD, FACS,(born July 31, 1953) is a trauma/general surgeon and formerly a Captain in the Medical Corps of the United States Navy.  While serving as a trauma surgeon at the Naval Medical Center in Portsmouth, Virginia, Dr. Davis rose to prominence for being lead clinical medical caretaker of the survivors of the USS "Cole" (DDG-67) attack in Yemen and the survivors from the USS "Firebolt" terrorist attack which occurred during operations to protect oil platforms in the Persian Gulf.  After transferring to Okinawa, Japan in 2004, then Commander Davis was deployed to Sri Lanka for the 2004 tsunami relief effort where the group from 3d Force Service Support Group (now 3d Marine Logistics Group) was sent to Point Pedro, Sri Lanka near the Tamil Tiger/Government civil war truce line.  In late 2005, Davis was Chief of Professional Services for the joint relief effort in Shinkiari in the Northwest Frontier Province of Pakistan after the earthquake which killed approximately 73,000 victims.  Additionally, in the spring of 2006, Davis led the medical relief effort in Java, Indonesia following the earthquake in that area.  Davis was frequently the face of US military relief operations in the 2004-2006 time period.

Jeff Bauman: Jeff Bauman Jr. is an American author.  He lost his legs in the Boston Marathon bombing and was the subject of a famous photograph taken in the aftermath of the bombing.  The 2017 film "Stronger" is based on a memoir of the same name he co-wrote, with Jake Gyllenhaal portraying him.

South Staffordshire line: The South Staffordshire line is a railway line that once connected Lichfield in Staffordshire, England with Dudley, formerly in Worcestershire.  However, it joined the Oxford, Worcester and Wolverhampton Railway's (OW&WR) line just north of Dudley Station, where it, in essence, continued to Stourbridge, in Worcestershire (Dudley and Stourbridge were later to become part of the West Midlands conurbation).  The section south of Round Oak remains open for freight workings only.  On 12 July 2013, in a suspected terrorist attack, a bomb was believed to have been detonated on the disused section of the line in Tipton, at Binfield Street, near Sedgley Road.

Supporting paragraphs: Jeff Bauman Boston Marathon bombing
Answer: Boston Marathon bombing