I am especially confused about transaction 10. why we don't consider it as an investing activity? Why the correct answer is operating activity? Interest revenue always refers to investment revenue.

Analyzing Chipotle's Transactions (10 of 11) (10) Chipotle received $1 cash as interest revenue earned during the quarter. Debit Credit 1 (10) Cash (+A) Interest revenue (+R, +SE) 1 From investors From bank +F +F 1/1/18 (a) (b) 1.184 From customers +0 (3) From sale of noncurrent asset +1 (6) From customers +0 (7) From earnings on investments +0 (10) From customers +0 (11) + Cash (A) - 186 300 54 2 1 44 290 5 80 39 41 1 260 42 164 94 731 (c)-I To purchase noncurrent assets (d) -F To repay notes payable to the bank (e) - To purchase investments in other companies (1) - To pay suppliers of food and paper products (2) - To pay suppliers of rental facilities, insurance, and advertising (4) - To pay to train employees (5) - To pay employees for working (8) - To pay suppliers and taxes (9) -0 To pay suppliers of utilities and repairs