What is the two principal thrust in physics?
(A) Unification and Reduction
(B) Unification and Oxidation
(C) Magnification and Reduction
(D) Simplification and Reduction

Hint :In order to solve this question, we are going to first know that what are the basic principal thrusts in physics and how they are defined and give the examples for both the thrusts that are applicable for the phenomena and the various laws in the field of the physics.

Complete Step By Step Answer:
The two main principal thrusts in physics are: Unification and Reduction.
Unification: It is the process of unifying the various distinct laws of physics into a single theory that explains or validates all the different phenomena. In other words, we can say that the diverse phenomena of nature are expressed in few terms of laws and concepts.
For example, the law of gravitation explains falling of objects on earth, planetary motion, motion of moon, etc.
Reduction: It is the process of breaking a complex system of the equations into simpler parts. The simpler equations are derived from the complex systems from its constituent parts. The laws of physics can be applied to these systems and we understand the working of the complex system.
Example: Temperature of a system is reduced to average kinetic energy.
Hence, option (A) is the correct answer.

Note :
Alternatively, we can also say that the Unification is a trial to correlate and unite various universal laws and basic phenomena of nature to explain an activity while reduction is an effort to solve a complex problem by breaking it into simpler parts. Both these form the principal thrust in physics.