­　　21. The author implies that making a sharp division between subject and object in physics is

­　　(A) possible in a measurement o object’s length and position, but not in a measurement of its energy

­　　(B) still theoretically possible in the small-scale world of atoms and electrons

­　　(C) possible in the case of observations involving the passage of a complete quantum

­　　(D) no longer an entirely accurate way to describe observation of the universe(D)

­　　(E) a goal at which scientists still aim

­　　22. The author’s use of the phrase “in a sense” (line 34) implies which of the following?

­　　(A) Quanta of extremely long wavelength are essentially graduated in inches.

­　　(B) quanta of one-inch wavelength are not precisely analogous to yardsticks graduated in inches.

­　　(C) Quanta of extremely long wavelength, in at least on e respect, resemble quanta of shorter wavelength.

­　　(D) quanta of on-inch wavelength and quanta of extremely long wavelength do not differ only in their wavelengths.(B)

­　　(E) quanta of one-inch wavelength must be measured by different standards than quanta of extremely long wavelength.

­　　23. According to the passage, the quantum theory can be distinguished from previous theories of physics by its

­　　(A) insistence on scrupulously precise mathematical formulations

­　　(B) understanding of the inherent interrelationship of perceiver and perceived

­　　(C) recognition of the need for sophisticated instruments of measurement

­　　(D) emphasis on small-scale rather than on large-scale phenomena(B)

­　　(E) regard for philosophical issues as well as for strictly scientific ones