Choose the suitable option from the given alternatives to represent the subject for a letter placing an order with M/S ABC Musical Instruments:

Placing order for musical instruments

The correct answer is Option (3) → Placing order for musical instruments

• The subject should clearly indicate the purpose of the letter.
• Since the letter is about placing an order, this option is the most appropriate.
• Other options like "Seeking information" or "Enquiring" suggest a request for details rather than an actual order.
• "Giving delivery" is incorrect because the sender is ordering the instruments, not delivering them.

Thus, the best choice is: "Placing order for musical instruments."