To unlock the "STAND YOUR GROUND" trophy in Detroit: Become Human, you must choose the "Stand Your Ground" and "Sacrifice" options during the chapter "FREEDOM MARCH".
Contrary to the other solution, you do not necessarily have to have taken the maintenance droid with you during "SPARE PARTS". There is one other option but it depends on your actions during The Stratford Tower. This alternative method will however void your ability to get another trophy if you haven't got it already:Here are your options:
*** Spoiler - click to reveal ***If the maintenance droid came with you during "SPARE PARTS", just choose "Stand Ground", "Stand Ground" and "Sacrifice" at the end of "FREEDOM MARCH" and Markus will be saved by that android.
If the maintenance droid did not come with you during "SPARE PARTS", you should make sure Simon gets out of "THE STRATFORD TOWER" unscathed. Do this by not raising any alarms. Choose "RUSE" when the full Jericho crew reach the broadcast floor to get rid of the two guards non-lethally. When in the room you MUST shoot the fleeing employee so that he doesn't raise the alarm. Finish your speech and jump off the roof, and Simon will be with you.
When you get to "FREEDOM MARCH", make the same decisions as above and instead of the maintenance droid sacrificing itself for you, Simon will do so instead.
The only situation in which you will not unlock this trophy despite choosing to stand your ground is if
As long as you fulfil the requirements this trophy will unlock when you reach the flowchart at the end of the chapter.