Three species of frogs, Rana pipiens, Rana clamitans, and Rana sylvatica, all mate in the same ponds, but they pair off correctly because they have different calls. This is a specific example of a barrier, called .
prezygotic ... behavioral isolation
prezygotic ... temporal isolation
postzygotic ... hybrid breakdown
prezygotic ... gametic isolation
postzygotic ... mechanical isolation

prezygotic ... behavioral isolation

Explanation:

Prezygotic barrier is a reproductive barrier that occurs when fertilization is prevented from occurring as a result of isolation leading to prevention of copulation, and as such there is no fusion of gametes for fertilization to take place, and eventually formation of zygote. Zygote is not formed as fertilization does not take place.

Behavioral isolation is a prezygotic reproductive barrier that prevents two or more different species to copulate together in order for fertilization to take place due to differences in behavior that is unique to each species. One of such behaviors is mating calls.

As a result of the differences in mating calls which is unique to each species of frogs mentioned in the question, only members of each species get attracted to themselves and mate with their members, thereby making it almost impossible for the three different species of frogs to mate together.

answer-

the statement that f(x) = |x+a| + b has exactly one x-intercept is sometimes correct.

solution-

it solely depends on b, whether the function will have one or two or zero x intercept.

this plot of the given function, f(x) = |x+a| + b will be the basic absolute value graph i.e v shape, with vertex translated to (-a, b), instead of origin.

1-   if b is zero, the graph will have exactly one x-intercept, at x= -a

2- if b is positive, the whole graph will be above the x-axis, hence it will have no x-intercepts.

3- if b is negative, the graph will be below the x-axis, hence it will have two x-intercepts.

∴ the statement is sometimes true.