Question: Which band, Marianas Trench or Car Seat Headrest, signed to Matador Records in 2015?

Context paragraphs:
Marianas Trench (band): Marianas Trench is a Canadian pop punk band from Vancouver, British Columbia, formed in 2001.  The band consists of members Josh Ramsay (lead vocalist, rhythm guitarist, pianist, songwriter, and occasional drummer), Matt Webb (lead guitarist and backing vocalist), Mike Ayley (bass guitarist and backing vocalist), and Ian Casselman (drummer, percussionist, and backing vocalist).  The band has released four full-length studio albums, the most recent titled "Astoria", released on October 23, 2015, along with 2011's "Ever After", 2009's "Masterpiece Theatre" and 2006's "Fix Me".  Their third album "Ever After" was nominated for a Juno Award.

Mariana Trench: The Mariana Trench or Marianas Trench is the deepest part of the world's oceans.  It is located in the western Pacific Ocean, an average of 200 km to the east of the Mariana Islands, in the Western Pacific East of Philippines.  It is a crescent-shaped scar in the Earth's crust, and measures about 2550 km long and 69 km wide on average.  It reaches a maximum-known depth of 10994 m (± 40 m ) at a small slot-shaped valley in its floor known as the Challenger Deep, at its southern end, although some unrepeated measurements place the deepest portion at 11034 m .  If Mount Everest were dropped into the trench at this point, its peak would still be over 1.6 km underwater.  In 2009, Marianas Trench was established as a United States National Monument.

Something Old / Something New: Something Old / Something New is the third extended play recorded by Canadian rock group Marianas Trench, released May 26, 2015 through 604 Records, Cherrytree Records, and Interscope Records.  It contains two songs originally recorded for the band's fourth studio album, "Astoria" (2015), and two tracks that pre-date the recording of their debut studio album, "Fix Me" (2006), from their Self-Titled EP "Marianas Trench" (2002).  The EP was released in promotion of "Astoria" and serves as a "thank you" to their fans.

Face the Music (EP): Face the Music: The EP (also known as Face the Music) is the title of the second extended play released by Canadian pop-rock group Marianas Trench.  Featuring popular songs from the group's most recent album, "Ever After" (2011), the EP marks Marianas Trench's first official US music release.  It was first released May 10, 2013 in New Zealand before being released in North America later that month, and was distributed through 604 Records, Cherrytree Records, and Interscope Records.

Never Say Die Tour (Marianas Trench tour): The Never Say Die Tour (Marianas Trench) is a Canadian concert tour by Canadian pop-rock band Marianas Trench (band) in support of their album "Astoria (Marianas Trench album)".

Marianas Trench discography: The discography of Marianas Trench, a Canadian pop rock band, consists of four studio albums, three extended plays, 18 singles and 18 music videos.  The band recorded and released their debut EP in 2002, entitled "Marianas Trench" containing 8 tracks.

Twin Fantasy: Twin Fantasy is the sixth studio album by indie rock act Car Seat Headrest.  Since its release in 2011, the album has amassed a cult following.

Car Seat Headrest: Car Seat Headrest is an American indie rock band originally from Leesburg, Virginia, United States, currently based in Seattle, Washington.  Begun as a solo recording project in 2010 by Will Barnes (born August 23, 1992), known professionally as Will Toledo, Car Seat Headrest released 12 albums on the music platform Bandcamp.  Signed to Matador Records in 2015, Car Seat Headrest began a tour in 2016 presenting material from their latest album "Teens of Denial" as a full band.  Toledo's work is notable for its large online cult following.  The group has received attention from publications including "Pitchfork", "Rolling Stone", "The New Yorker" and "Paste", amongst others.

Teens of Denial: Teens of Denial is the tenth studio album by American indie rock band Car Seat Headrest.  It was released on May 20, 2016 by Matador Records, serving as the band's second album for the label and the first to consist of newly recorded material.

Teens of Style: Teens of Style is the 9th studio album by American indie rock band Car Seat Headrest, released on October 30, 2015.  It was their first album recorded for Matador Records.  Intended as an introductory compilation for new listeners, it features reworked newly recorded versions of songs originally released between 2010 and 2012, with the addition of one new composition.

Supporting paragraphs: Marianas Trench (band) Car Seat Headrest
Answer: Car Seat Headrest