Is "Sabhi chhatragan upasthit the" correct?

Why

Maanasi's instinct — that naming 'everyone' explicitly adds clarity — makes sense for many sentences, but not when the word already right next to it has silently packed that meaning in. In Hindi, the suffix 'गण' itself means 'a group/collection of', so 'छात्रगण' already means 'the group of students' — i.e. all the students together, not one student. Adding 'सभी' (all) in front doesn't clarify anything new; it repeats a meaning ('all of them') that 'गण' was already carrying, which is the same पुनरुक्ति दोष (redundancy) seen with 'अपनी स्वयं' earlier in this chapter. The correct sentence simply drops the redundant word: 'छात्रगण उपस्थित थे' or 'सभी छात्र उपस्थित थे' — either form alone is complete. Test it: 'छात्रगण उपस्थित थे' already reads as 'the whole group of students was present' — adding 'सभी' answers a question ('were they all present?') that the word 'गण' had already settled. Her brother is right: 'छात्रगण' already means 'all the students' as a group — adding 'सभी' in front is redundant.