Explanation:

- The 'Payment and Settlement Systems in India: Vision 2019 - 2021' report aims to enhance the digital transaction landscape.

- It projects a significant increase, expecting more than a fourfold jump in digital transactions by December 2021.

- The specific number expected is one of the choices provided.

Let's consider the options:

- Option 1: 2000 crore - This doesn't align with the "more than 4 times" increase.

- Option 2: 7,707 crore - This is plausible but not the number expected as per reports.

- Option 3: 8,707 crore - This aligns with the expected more than four times increase.

- Option 4: 5,707 crore - Less than the expected milestone as per objectives.

- Option 5: 6,707 crore - Also less than the ambitious target outlined.