Final answer:
CINAHL (Option 2) has a better chance of yielding further results for the research topic about the efficacy of HPV vaccine.
Step-by-step explanation:
Based on the information provided, CINAHL has a better chance of yielding further results for your research topic about the efficacy of HPV vaccine.
CINAHL is a database specifically focused on the field of nursing and allied health, which includes topics such as vaccines and public health.
As a specialized database, it is more likely to provide targeted and comprehensive results related to your topic.
On the other hand, PubMed is a general life sciences database that covers a wide range of biomedical topics, so it may not have as specific and in-depth coverage of your particular research area.
Hence, the correct answer is Option 2. CINAHL.