Answer:
They are effective for long periods of time
Step-by-step explanation:
Alpha and Beta interferons are part or form of Interferons. The Alpha interferons is derived from leukocytes infected with virus, while the Beta is derived from fibroblasts infected with virus.
Both of them have various mechanism of action including:
1. they bind to the surface of uninfected cells.
2. they initiate manufacture of antiviral proteins.
3. they disrupt stages of viral multiplication.
4. they initiate transcription.
Hence, in this case, the correct answer is "they are effective for long periods" because they are not.