Kaplan kit

Hello tutor,
Compared to ordinary secured loan notes, which of the following statements is true when considering convertible secured loan notes?

A Likely to be more expensive to service because of their equity component
B Likely to be less expensive to service because of their equity component
C Likely to be more expensive to service because converting to equity requires he holders to make additional payments
D Likely to be less expensive to service because they must rank after ordinary secured loan stock

Answer is B
What “expensive to service” means? Is it interest rate?