Adaptive reactions to fear can be seen in all the following ways except
a.
fear can unite individuals
b.
fear improves sensory perception
c.
fear can lead to irrational behavior
d.
fear can motivate one toward action

My guess is C. Fear can lead to irrational behavior.

Because that seems more negative than adaption.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.