Sir,
The section is read as under
SECTION 16(3) A registered person making zero-rated supply shall be eligible to claim refund under either of the following options, namely:––
(a) he may supply goods or services or both under bond or Letter of Undertaking, subject to such conditions, safeguards and procedure as may be prescribed, without payment of integrated tax and claim the refund of unutilized input tax credit; or
(b) he may supply goods or services or both, subject to such conditions, safeguards and procedure as may be prescribed, on payment of integrated tax and claim refund of such tax paid on goods or services or both supplied, in accordance with the provisions of section 54 of the Central Goods and Services Tax Act or the rules made thereunder.
Further, the option in general language refer to the phrase that the assessee at his discretion can decide whether to make export with payment or without payment.
Any query further please let me know.