true testing means that a serious effort is made to falsify ("disprove") each possible
explanation.
true or false?

The statement given about the true testing mechanism is false.

Testing is the way toward assessing a framework or its component(s) with the plan to discover whether it fulfills the predefined necessities or not. It is a process of executing a framework so as to distinguish any holes, blunders, or missing prerequisites in as opposed to the real necessities.  

The concept of true testing is not to falsify all possible explanation. It means to come up with a solution which is true in all aspects.

the answer to your question is b

hi~~

i would say that hybridization occurs frequently in nature, because there are many types of hybrids that have occurred naturally, such as the mule (male donkey + female horse)