Which phrase from this excerpt from act 1 of Henrik Ibsen's A Doll's House suggests that Krogstad is prone to engage in crime and may, in fact, be a criminal?

The answer to this question would be

diseased moral character

The phrase from the excerpt that suggests that Krogstad is prone to engage in crime and may, in fact, be a criminal is the following one:

diseased moral character

It is the only option that talks about somebody being a bad person, which is what Krogstad is. The other options do not show that moral ambiguity this option does.