The hierarchy generally mentioned across texts includes five indriyas, manas, buddhi, and kshetranga. Buddhi is influenced by the trigunas (sattwa, rajas, and tamas), but the trigunas may not be components of buddhi as they are just states of buddhi. According to my understanding, the apt place for trigunas to reside is only kshetragna, as the remaining seven are under its control. However, the apparent contradiction is that kshetagna is merely a sakshi and does not involve itself in any activity. So, where exactly do the trigunas reside? If they reside in kshetragna, as mentioned that brahman united with trigunas, then kshetragna is said to be influencing the buddhi and hence the remaining components, which may violate the property of being sakshi. The following excerpt contains all the relevant details.
Having created these, the Supreme Deity, O Bharata, united with them Sattwa, Rajas, Tamas, Time, Consciousness of functions, and Mind forming the sixth. That which is called the Understanding dwells in the interior of what thou seest above the soles of the feet and below the crown of the head. In man the senses (of knowledge) are five. The sixth (sense) is the Mind. The seventh is called the Understanding. The Kshetrajna or Soul is the eighth. The senses and that which is the Actor should be ascertained by apprehension of their respective functions. The conditions or states called Sattwa, Rajas, and Tamas, depend upon the senses for their refuge or formation. The senses exist for simply seizing the impressions of their respective objects. The Mind has doubt for its function. The Understanding is for ascertainment. The Kshetrajna is said to be only an inactive witness (of the functions of the others). Sattwa, Rajas, Tamas, Time, and Acts, O Bharata, these attributes direct the Understanding. The Understanding is the senses and the five fore-mentioned attributes. When the Understanding is wanting, the senses with the mind, and the five other attributes (viz., Sattwa, Rajas, Tamas, Time, and Acts) cease to be. That by which the Understanding sees is called the eye. When the Understanding hears, it is called the ear. When she smells, she becomes the sense of scent; and when she tastes the various objects of taste, she comes to be called by the name of tongue. When again she feels the touch of the various objects of touch, she becomes the sense of touch. It is the Understanding that becomes modified diversely and frequently. When the Understanding desires anything, she becomes Mind. The five senses with the Mind, which separately constitute the foundations (of the Understanding), are the creations of the Understanding. They are called Indriyas. When they become stained, the Understanding also becomes stained. 3 The Understanding, dwelling in Jiva, exists in three states. Sometimes she obtains joy; sometimes she indulges in grief; and sometimes she exists in a state that is neither pleasure nor pain. Having for her essence these conditions or states (viz., Sattwa, Rajas, and Tamas), the Understanding resolves through these three states.
[Section 286, Mokshadharma Parva, Santi Parva, The Mahabharata]
The question is: where exactly the trigunas reside or arise?
