Scientific theories are always (a. testable b. true c. unreliable). a theory may be changed as a result of (a. competing theories b. new observations c. untested hypotheses) complete the sentences with those options.

1. A. testable

2.new observations

Explanation:

A scientific theory is the one which explains the cause of a natural phenomena through observatory and experimentation approach. It is valid, accurate and acceptable worldwide.

1. It is testable by implementation of suitable methodology for the purpose of proving the cause of the natural phenomena occurring in nature.

2. A the explanation of the theory can be changes on the basis of the new observations obtained after implementation of new technology and methodology.