Okay, here's the difference between positive and negative assurance as it relates to the FS… Positive assurance means that the auditor feels that the financial statements are fairly presented in all material respects in accordance with GAAP (or whatever the reporting framework is). Negative assurance means that the auditor only performed limited procedures (i.e., not as extensive as an audit) and is not aware of any material modifications that would need to be made to make the FS conform with GAAP.
Now, as the explanation to c. states, you can provide negative assurance regarding compliance, which means that you perform limited procedures and state whether or not you are aware of anything that caused you to believe that the company failed to comply with the requirements. Notice that you're not making the stronger statement that the entity complied in all material respects. You're merely stating that you're not aware of anything that would cause you to believe that the entity failed to comply. It's a lower level of assurance.
Choice b is saying that you're basically auditing and providing an opinion (positive assurance) on those three types of reports.