Answer:
a. road or pipeline
b. permanent structure that keeps habitat patches from being rejoined
d. something that prevents a species from accessing its entire home range
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Option A refers to roads or pipelines that can act as physical barriers in a fragmented habitat, preventing or restricting the movement of species between habitat patches.
Option B refers to permanent structures, such as buildings or fences, that can fragment habitat patches and prevent them from being rejoined, creating isolated fragments of habitat that can negatively impact species' ability to move and disperse.
Option D refers to any factor or obstacle that prevents a species from accessing its entire home range, such as a physical barrier like a river or a human-made structure like a fence or a wall. This can also contribute to habitat fragmentation and restrict species' movement and access to resources.
Option C, on the other hand, is not an example of a barrier in a fragmented habitat, as it refers to a piece of land that connects habitat patches, which can actually help to mitigate the effects of habitat fragmentation by providing connectivity for species movement.