Question

around this time next week,we_________________through streets of london

a have strolled
b will be strolling

Answer 1

The correct option is ‘b’.

Around this time next week, we will be strolling through streets of London.

Explanation

We use Future Continuous Tense for an action over a period of time. It means at some time in future we will be in the middle of an action.

Example: She will be working all day tomorrow.

Answer 2

The correct answer of your question is "will be strolling" option "b"..

The easiest way to understand the reason is that " because the tense above is showing that something is going to happen in the future So simply we will use the future tense and the course  of action will be happening here so the future continuous tense will be used".
The other option is not a future tense so the answer will be "option b"