Question: What type of instrument is the Sagar Veena, invented by the father of musician Noor Zehra?

Context paragraphs:
Sakharam Rao: Sakha Rama Rao (Sakharam Rao) is an Indian musician credited with having re-introduced the south Indian chitravina (or "gotuvadyam") to the concert scene.  However, it was his father, Srinivasa Rao, who made the pioneering effort towards the reincarnation of the chitravina in modern times.  He was an ardent music lover and an amateur artiste himself.  He started experimenting with a slide on the tanpura (a four-stringed instrument, usually used as a reference drone in Indian music).  Sakha Rama Rao was drawn to this instrument since childhood.  He was able to perceive its tremendous potential to produce high-class music.  He re-designed this instrument as a fretless veena with its usual set of seven strings - four strings on the top and three in the side for drone and rhythm.  He put in arduous practice on this instrument and gave occasional performances.  Since he was not aware of the history of the instrument, he gave it a new name - gotuvadyam.  This is because, he used to casually refer to the slide as 'gotu'.  'Vadyam', in Sanskrit and many other Indian languages, means instrument.  Thus, 'gotuvadyam' was a literal name for an instrument played with a slide.  Several decades later, Ravikiran, along with a few other scholars, studied about the origins of the instrument and eventually restored the more traditional name, chitravina.  Sakha Rama Rao was a "musicians' musician" and trained many great artists like Gotuvadyam Narayana Iyengar and Semmangudi Srinivasa Iyer.  Soon there were several others who started performing on the chitravina (gotuvadyam).

Saraswati veena: The Sarasvati vīṇa (also spelled Saraswati vina) (Tamil: வீணை , Bengali: সরস্বতী বীণা , Sanskrit: वीणा (vīṇā), Kannada: ವೀಣೆ , Malayalam: വീണ, Telugu: వీణ ) is an Indian plucked string instrument.  It is named after the Hindu goddess Saraswati, who is usually depicted holding or playing the instrument.  Also known as "raghunatha veena" is used mostly in Carnatic Indian classical music.  There are several variations of the veena, which in its South Indian form is a member of the lute family.  One who plays the veena is referred to as a "vainika".

Chitti Babu (musician): Chitti Babu (October 13, 1936 – February 9, 1996) was a renowned classical musician from India, and arguably one of the greatest Veena artistes, in the Carnatic Music genre of South India, who became a legend in his own lifetime.  His name was synonymous with the musical instrument Veena, and he was and still is known in the Carnatic Music world, simply as Veena Chitti Babu.

Gottuvadhyam: The chitravina (also known as chitra veena, chitraveena, chitra vina, hanumad vina, or mahanataka vina) is a 20 or 21-string fretless lute in Carnatic music.  Around the late 19th and early 20th centuries, it started to be known by another name, Gotuvadyam (often mis-spelt as gottuvadyam, gottuvadhyam, kottuvadyam etc.), which was bestowed upon it by Sakha Rama Rao from Tiruvidaimarudur, who was responsible for bringing it back to the concert scene.

Misr veena: Misr veena, (pronunciation:] मिश्र वीणा ), is a plucked stringed musical instrument of Indian origin.  It was invented by veena maestro Suvir Misra and is used in Indian classical music.

Jungle Queen (2001 film): Jungle Queen is a Pakistani film directed by Syed Noor and written by his then-wife, Ruckhsana Noor.  The film stars Saima (aka Saima Noor after marrying director Syed Noor in 2005) as the title character.  She is a female Tarzan type who lives in the jungle, swings on vines, rides elephants, etc.  This standard jungle adventure story has a romantic subplot and, being a Lollywood film, some song and dance numbers.

Acımak: Acımak ("Feeling Pity") is a novel by Turkish author and playwright Reşat Nuri Güntekin, written in 1928.  The novel tells the tragic story of a teacher named Zehra.  Reşat Nuri Güntekin tells dramatic life stories from the perspectives of Teacher Zehra, who are hardworking but brutal against the weaknesses and her father Mursit.  The author gives important clues to the period of civil servant life, as well as the clashes and incompatible relations in the business and social life of a young graduate, idealist teacher.

Bobbili Veena: Bobbili veena is a large plucked string instrument used in Carnatic classical music.  The Veena is named after Bobbili, a place where it was invented.  In 2011 the musical instrument got a Geographical Indication tag from the Government of India.

Veena: The veena (Sanskrit: वीणा , IAST: vīṇā), also spelled as vina or beena or bina, is a multistringed chordophone of the Indian subcontinent.  It is an ancient musical instrument that evolved into many variations, such as lutes, zithers and arched harps.  The many regional designs have different names such as the Rudra veena, the Saraswati veena, the Mohan veena and others.

Noor Zehra: Madam Noor Zehra Kazim is a Pakistani Sagar Veena player.  She is the daughter of lawyer and activist Raza Kazim who invented Sagar Veena - a stringed instrument similar to Vichitra veena and Chitra Veena.  Together with her father she runs Sanjan Nagar Institute of Philosophy and Arts, and is the only performer of Sagar Veena since its creation in 1971.  With a career spanned over four decades, she has performed both domestically and internationally, achieving critical appraisal for instrument, as well as her Indian style of music being a non-Indian.

Supporting paragraphs: Noor Zehra Gottuvadhyam
Answer: fretless lute