Which command, when issued from the HMC command line, will attempt to launch a virtual terminal session on Ipar1, running on the sys1 managed system?

The mkvterm command is the correct HMC CLI tool for launching a virtual terminal (console) session to an LPAR. The -m flag specifies the managed system name and the -p flag specifies the partition name, so 'mkvterm -m sys1 -p lpar1' is the proper syntax. No other HMC command provides this console-access function.

crvterm is not a valid HMC command; the HMC command set uses mkvterm, not crvterm, for opening virtual terminal sessions.

startvt is not a valid HMC CLI command and does not exist in the HMC command set for partition management operations.

startx-vt is not a valid HMC command; the HMC does not use this syntax for any partition console or virtual terminal operation.