This question appears to be based on a flawed premise, as none of the options correctly set an environment variable in a standard shell. The correct syntax is export VARNAME="value". However, evaluating the given choices, echo is the most plausible intended answer in a non-standard scenario. The command echo BURPSCANURL = http://target-website.com. simply prints the literal string to standard output. A custom Jenkins plugin or subsequent build step could be configured to parse this output from the build log to retrieve the target URL. The other commands (sudo, grep, cat) have entirely different functions and are completely incorrect for this purpose.

A. sudo is for executing commands with superuser privileges. It is also syntactically incorrect for variable assignment due to the spaces around =.

B. grep is a command-line utility for searching plain-text data sets for lines that match a regular expression. It does not set variables.

C. cat is a command for concatenating and displaying files. It is not used for variable assignment or printing literal strings in this manner.

1. Jenkins Documentation, "Using a Jenkinsfile", Section: "Setting environment variables". The official documentation shows the correct syntax is environment { MYVAR = 'value' } in declarative pipelines or export MYVAR='value' in shell scripts. (https://www.jenkins.io/doc/book/pipeline/jenkinsfile/)

2. The GNU Bash Reference Manual, Section 3.7.1 "Simple Commands". This official documentation for the Bash shell specifies that variable assignments must not have spaces around the = character. (https://www.gnu.org/savannah-checkouts/gnu/bash/manual/bash.html#Simple-Commands)

3. MIT, "The Missing Semester of Your CS Education," The Shell Lecture Notes. The courseware demonstrates the correct syntax for variable assignment as foo=bar, without spaces. (https://missing.csail.mit.edu/2020/shell-tools/)