Question

In many cases in physics, one has to deal simultaneously with collective and single-particle excitations of the system. The collective excitations are usually bosonic in nature while the single-particle excitations are often fermionic. One is therefore led to consider a system which includes bosons and fermions. Hence, ________. Which of the following options is most likely to follow the paragraph given above?

• A. in this book, we discuss application of bosonic particles and their consequences on physics.
• B. in this book, we discuss application of general algebraic theory of mixed Bose–Fermi systems to atomic nuclei.
• C. in this book, we discuss excitations of collective and single particles separately.
• D. in this book, we prove how collective excitations are bosonic and singular excitation are fermionic.
• E. in this book, we prove that collective and singular excitation cannot exist together.

Hint:

In paragraph-completion type questions, always look for the option that {extends the argument logically} rather than restating or contradicting it.

Answer 1

The Correct Option is B

Step 1: Understand the context.
The paragraph explains that in physics, both bosonic Collectiv(E) and fermionic (single-particl(E) excitations must be studied together. This naturally leads to mixed Bose–Fermi systems.
Step 2: Match the options.
- Option A focuses only on bosonic particles — incomplete, since both bosons and fermions are discussed.
- Option B introduces the general algebraic theory of mixed Bose–Fermi systems, exactly what is implied by the need to handle both bosons and fermions together. This is a precise continuation.
- Option C suggests discussing collective and single excitations separately, but the paragraph emphasizes their simultaneous study.
- Option D just restates the definitions Bosonic vs fermioni(C) without advancing the idea.
- Option E incorrectly suggests that both cannot coexist, which contradicts the passage.
Step 3: Conclude.
The logical continuation is Option B, since it connects directly with the idea of dealing with a combined Bose–Fermi system and its application. \[ \boxed{\text{Correct Answer: (B)}} \]