Explanation:

Sure, here are the explanations for the options provided:

- Option 1: Expressly

- An actual breach occurs clearly and overtly.

- The breach is directly and unmistakably communicated.

- Option 2: Impliedly

- An actual breach occurs through actions suggesting non-performance.

- There's an inferred failure, though not directly stated.

- Option 3: Either (a) or (b)

- An actual breach can be through either explicit or implicit conduct.

- Both forms of breach demonstrate non-fulfillment of obligations.

- Correct Answer: Either (a) or (b)

- Option 4: Neither (a) nor (b)

- This option suggests a breach cannot be either express or implied.

- Contradicts general legal understanding of breaches.