Question 14

Soil temperature may affect flea infestation levels.

The author suggests that fluctuations in flea levels may vary based on the age of the host and could be influenced by soil temperature. This implies that soil temperature plays a role in determining the infestation levels of fleas on different age groups of hosts.

A) fluctuations in the growth rates of parasitized hosts

This option is incorrect as the passage does not mention growth rates of parasitized hosts being affected by soil temperature. The focus is specifically on flea infestation levels rather than the growth rates of the hosts themselves.

B) age-based changes in immune responses

This option is also incorrect. While the passage discusses immune responses in relation to host age, it does not link these responses to soil temperature. The hypothesis presented centers on how soil temperature may influence flea levels, not immune responses.

C) flea-induced mortality

This option is incorrect because the passage does not suggest that soil temperature affects mortality rates caused by fleas. Instead, it focuses on the potential impact of soil temperature on flea infestation levels, not on the mortality aspect.

D) seasonal changes in mortality rates among fleas that infest wood mice

This choice is incorrect as well. The passage does not address mortality rates of fleas directly in relation to soil temperature or seasons; rather, it discusses the impact of soil temperature on flea infestation levels without linking it to mortality rates.

E) flea infestation levels

This option is correct as the passage clearly states that the levels of flea infestation may fluctuate based on soil temperature. The author supports the hypothesis that environmental factors, such as soil temperature, can influence the dynamics of flea populations on hosts.

Conclusion

The correct answer is E, as it directly addresses the hypothesis presented in the passage regarding the impact of soil temperature on flea infestation levels. All other options fail to connect the concept of soil temperature with the factors they propose, making E the only choice that aligns with the author’s discussion.