Question: Plymouth Regional High School is located in what county?

Context paragraphs:
Plymouth, New Hampshire: Plymouth is a town in Grafton County, New Hampshire, United States, in the White Mountains Region.  Plymouth is located at the convergence of the Pemigewasset and Baker rivers.  The population was 6,990 at the 2010 census.  The town is home to Plymouth State University, Speare Memorial Hospital, and Plymouth Regional High School.

Lower Camden County Regional High School: Lower Camden County Regional High School was founded in 1939 in Lindenwold, New Jersey, United States.  As the school district grew, in 1958 Edgewood Regional High School was built and Lower Camden County Regional was renamed Overbrook Regional High School as part of Lower Camden County Regional School District #1.

Northern Valley Regional High School at Demarest: Northern Valley Regional High School at Demarest is a comprehensive four-year public high school serving students from several municipalities in Bergen County, New Jersey, United States.  The high school serves students from the suburban communities of Closter, Demarest and Haworth.  The school is one of two high schools that are part of the Northern Valley Regional High School District, the other being Northern Valley Regional High School at Old Tappan, which serves students Harrington Park, Northvale, Norwood and Old Tappan, along with students from Rockleigh, who attend as part of a sending/receiving relationship.

Hamilton-Wenham Regional High School: Hamilton-Wenham Regional High School (HWRHS) is a public high school in South Hamilton, Massachusetts, United States.  It is the only high school in the Hamilton-Wenham Regional School District, which has its administrative offices in Wenham, Massachusetts.  The school's athletic teams are called the Generals, named after General George S. Patton, who lived in Hamilton.  Students' average SAT scores are above the state average and the school regularly sends top students to Ivy League schools.  In 2010, Hamilton-Wenham Regional High School placed in the top 10% of Massachusetts schools, ranking number 12, according to the Boston Magazine's Annual "Best Schools" list.  In 2011, Hamilton-Wenham Regional High School moved up to number 9 in Boston Magazine's "Best Schools" list.

Eastern Intermediate High School: Eastern Intermediate High School was a public high school that served students in grades nine to ten from three communities in Camden County, New Jersey, United States, as part of the Eastern Camden County Regional High School District.  The school served students from Berlin Borough, Gibbsboro and Voorhees Township.  The high school was located in Voorhees Township.  In the past students that finished tenth grade moved on to Eastern High School, (now renamed Eastern Regional High School) for eleventh and twelfth grades.  The district was established in 1965, with 35 professional staff and 495 students, and Eastern Intermediate High School was completed in 1992.

Highland Regional High School: Highland Regional High School is a four-year comprehensive public high school located in Blackwood, serving students in ninth through twelfth grades from Gloucester Township in Camden County, New Jersey, United States.  The school is part of the Black Horse Pike Regional School District, which also includes Timber Creek Regional High School and Triton Regional High School (which serves students from Bellmawr and Runnemede).  The school is accredited by the New Jersey Department of Education.

Newfound Regional High School: Newfound Regional High School (NRHS) is a public secondary school in Bristol, New Hampshire, United States.  Surrounding towns that attend NRHS are Bristol, New Hampton, Groton, Bridgewater, Danbury, Alexandria, Hill, and Hebron.  The school is part of the Newfound Area School District (NASD) and was originally named Newfound Memorial High School.  It was originally located where Newfound Memorial Middle School currently stands until the present high school building was constructed in 1989.  Newfound Regional High School was awarded "NH Excellence in Education" in 2010.  Newfound Regional High School's motto is "Choose your path to success...make a commitment."

Timberlane Regional High School: Timberlane Regional High School is located in Plaistow, New Hampshire, and serves as a regional high school for the towns of Atkinson, Danville, Plaistow, and Sandown, New Hampshire.  The school was built in 1966 and is a part of the Timberlane Regional School District.  Timberlane Regional High School is a co-educational school for grades 9-12.  The school has won the 1996, 1997 and 2014 Excellence In Education Award.  As of 2005, the school has approximately 1,400 students on roll.  The school mascot is the owl.  The school is regionally accredited for its award-winning wrestling team, which holds 23 NH State Wrestling Champions titles, as of 2015.

Edgewood Regional High School: Edgewood Regional High School is the original name of Winslow Township High School that opened in 1958.  Though the mailing address of the school was Atco, New Jersey, the site actually resided in a section of Winslow Township known as Tansboro.  The school's name changed in 2001 due to the breakup of the Lower Camden County Regional School District (L.C.C.R.H.S.) which consisted of Edgewood and Overbrook Regional High School.  The buildings were turned over to the Winslow Township School District and became Winslow Township High School.  Likewise Overbrook dropped the "regional" part of its name and became Overbrook High School (part of the Pine Hill Schools).  At the time of the district dissolution, Edgewood was receiving students from Winslow Township, Waterford Township, and Chesilhurst Borough.  Waterford Township reached an agreement with Hammonton to send its students to Hammonton High School rather than the newly renamed Winslow Township High School.

Plymouth Regional High School (New Hampshire): Plymouth Regional High School (PRHS) is a public secondary school in Plymouth, New Hampshire, United States.  Surrounding towns that attend PRHS are Ashland, Holderness, Campton, Rumney, Wentworth, Warren, Ellsworth, Waterville Valley and Thornton.  Bruce Parsons is the current principal.  The facility, opened in 1970, is located on Old Ward Bridge Road in Plymouth.  It also housed Plymouth Elementary School until 1990.  Plymouth Regional was known as Plymouth Area High School until 1991.  The school colors are navy blue and white.

Supporting paragraphs: Plymouth Regional High School (New Hampshire) Plymouth, New Hampshire
Answer: Grafton County