Question

read the passage and then answer the question.
symbiotic relationships, which occur when one organism is dependent on another organism for survival, are typically categorized into three different types of relationships: parasitism, mutualism, and commensalism. in each of these relationships, the organisms involved are benefited or harmed in different ways.
parasitic relationships are often the most familiar types of symbiotic relationships. a common example is a flea living on a dog. in cases like these, the parasite gains a viable habitat to support its life cycle, while the host is harmed.
in a mutualistic relationship, on the other hand, both organisms in the relationship are better off because of their arrangement; that is, they benefit mutually from their interactions. for example, lichen is composed of two organisms, an alga and a fungus. the fungus acts like a sponge, holding on to water that the alga needs. at the same time, the alga is constantly converting sunlight into energy, so the fungus, which cannot perform this function for itself, benefits from a reliable energy source. lichen is, in turn, engaged in a commensalistic relationship with the tree that it grows on. in a commensalistic relationship, one organism benefits and the other organism neither benefits nor suffers. the tree provides lichen with a place to grow, but the tree is unaffected.
what is the meaning of viable as used in the passage?
able to find
pleasant or luxurious
usable
unwilling or forced

Explanation:

To determine the meaning of "viable" in the passage, we analyze the context. The passage states a flea (parasite) gains a "viable" habitat to support its life cycle. We evaluate each option:

• "able to find": The habitat isn't about the ability to find but about its suitability for the flea's life cycle. Eliminate this.
• "pleasant or luxurious": The passage doesn't suggest the habitat is pleasant or luxurious, just that it supports the flea's life cycle. Eliminate this.
• "usable": A usable habitat would be one that can support the flea's life cycle, which fits the context.
• "unwilling or forced": This has nothing to do with the habitat's suitability for the flea. Eliminate this.

Answer:

usable