Question

in a decades - long field trial at an agricultural experiment station in iowa, strips of clover are planted between rows of corn; bacteria living inside the clovers root nodules receive sugars from the plant, while they in turn convert atmospheric nitrogen into a form the clover can use, forming a textbook case of ______ between species.
1 mark for review
which choice completes the text with the most logical and precise word or phrase?
a symbiosis
b competition
c evolution
d resilience

Explanation:

To solve this, we analyze each option:

• Option A: Symbiosis is a close and long - term interaction between different species where both (or at least one) benefit. In the text, bacteria get sugars from clover and clover gets usable nitrogen from bacteria, so it's a mutual - benefit interaction, fitting symbiosis.
• Option B: Competition is when species compete for resources, but here both are benefiting, not competing.
• Option C: Evolution is about change in species over time, not about the interaction between these two species in the described way.
• Option D: Resilience is about the ability to recover from disturbances, which is not related to the interaction between clover and bacteria here.

Answer:

A. symbiosis