Backreferences — check yourself

Question 1

Which text does (\d)\1 match?

Accepted Answer

11

Answer

12

Answer

1

Answer

21

Question 2

How do you refer to a group named year in a replacement?

Accepted Answer

$<year>

Answer

\k<year>

Answer

$year

Answer

\year

Question 3

Why does \b(\w+)\s+\1\b end with \b?

Accepted Answer

So the copy must be a whole word, not the start of a longer one

Answer

To make it faster

Answer

It is required by the i flag

Answer

To capture the space