The stimulus states: K and G were the only ones able to tell the press about the institute. K had reason to do it. G did not. So, K must have done it.
Answer (B) states: C and W had the motive. But W would have been too scared. So, C must have done it.
Answer (C) states: H and L had the access. H had reason to do it. L did not. So, H had to do it.
When you break down the arguments into their parts, you can see that (B) and (C) are slightly different. (C) states that L did not have a reason to do it, while (B) states that W would have been too scared. The stimulus only states that G did not have a reason to do it. Therefore, answer (C) more closely parallels the reasoning than answer (B).