Q21

[ShehryarB30]

Could you pls explain this

[ohthatpatrick]

From the setup, we can think about who each character can pass to:

J can pass to K/L
K can pass to L/M
L can pass to K/M
M can pass to anyone, but since no one else can pass to J, M has to always pass to J.

For Q21, we need a pair that can hand it back and forth to each other.
J can pass to K or L, but neither K nor L can pass back to J.
M can pass to J, but J can't pass back to M.
K and L can each pass to M, but M can't pass back to them (M must pass to J)

So, the only pair that can pass back and forth is K and L.

That makes (C) the correct answer.