The code below is what looks at it.
They need to be identical. They don't need to be anything special.
The mood enhancer and primitive serum should be enough to meet the requirements.
Just all 10 need to be made the same. How similar is the question.
It does mention batch size below of 10. If that is the case you would need to purchase all 3 batch sizes before this can be completed. There could be a reason for that. That may be to insure they are identical.
Python:
label sister_vaginal_taboo_break_revisit_quest_1(the_person):
mc.name "I've got some serum for you and your friends."
call screen serum_inventory_select_ui(mc.inventory, the_person, batch_size = 10)
$ the_serum = _return
if _return == None:
mc.name "Actually, I forgot to grab them from the office. I'll be back another time."
"[the_person.possessive_title] pouts, but nods her understanding."
return