This is an example of a cause and effect relationship.
Answer:
The point of view of the author establishes that humans are the biggest threat to sea otters because they endanger the environment of the sea otters and don't rebuild it.
Explanation:
First of all, if we understand the author's perspective we can see that he claims sea otters have lived in environments with strong human influence. That has made them look for their own space and to migrate to look for places where they can live. Making them run risks in a journey and clashing with other species, as well as with them. Factories, immoderate logging, hunting, breaking of the food chain. Humans have had a very large and negative impact on them, without doing enough efforts to fix their effects on the sea otter's habitats.
The best revision of this sentence is the following:
The lawyer presented a clear argument to the jury (it was unbelievable how influenced they were by his case) in the hopes of winning the trial.
A pair of parentheses needs to be used in order to separate this information from the rest of the sentence and facilitate reading and comprehension. The information in the parentheses is related to the meaning of the sentence but in some way it interrupts the flow, so a pair of parentheses is necessary in order to indicate this.