UNIX was programmed in C.
The Unix operating system. The first versions of the Unix operating system were written in the "B" language, and later written in "C", which was invented in order to develop Unix on the PDP-11 machine.
Unix was created first. The C programming language was created for Unix.
Unix is primarily written in the C language, with some small snippets of assembler code for low level bootstraps.
C. Schirmer has written: 'Programming in C for UNIX' -- subject(s): C (Computer program language), UNIX (Computer file)
Unix.
The C programming language was originally created for Unix. Unix, and most other Unix-like systems such as Linux, are written almost entirely in C.
Ben Hunsburger has written: 'UNIX quick reference' -- subject(s): C (Computer program language), UNIX (Computer file), XENIX (Computer file)
Unix was first developed in assembly language in 1973. Academic circles studied Unix around this time and even into the early 1980's. It was first licensed in 1974.
The C language has implementations for all popular platforms, including Unix.
The language in which the document was first written is not specified in the question.
Douglas W. Topham has written: 'A system V guide to UNIX and XENIX' -- subject(s): UNIX System V (Computer file), XENIX (Computer file) 'The first book of UNIX' 'UNIX and XENIX' -- subject(s): UNIX (Computer file), XENIX