Explanation:

- "ATM" stands for Automated Teller Machine.

- Option 1: Transfer

- Transfer refers to moving money from one account to another.

- It is a feature of ATM usage but not the meaning of "T."

- Option 2: Teller

- Teller in ATM stands for an electronic teller, as in a bank teller.

- ATMs perform the functions similar to a human bank teller.

- Option 3: Transaction

- Transaction involves any banking activity, like withdrawal.

- It is a part of using an ATM but not what "T" stands for.

- Option 4: Trunk

- Trunk is not related to ATM's functions.

- Hence, it is not relevant.

The correct answer is Option 2: Teller.

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