The answers are C, F and I.

In the first blank, the analogy to the laws of physics and the exploration of certain characteristics or rules suggest a need for a term that conveys predictability and order. For the second blank, the description of movements as initially chaotic points to the necessity of a word that signifies disorder and lack of a clear pattern. The third blank, emphasizing the emergence of streams of movement and the pull for others to join, calls for a term that captures the self-sustaining nature of the channels.

Blank (i):
A. apparent contradictions: This option suggests that viewing people as 'social atoms' following simple rules may lead to apparent contradictions. However, the sentence is more focused on the discovery of certain characteristics or rules, and the term "apparent contradictions" does not align with the idea of discovering lawlike regulations.
B. unproductive tendencies: This choice implies that viewing people as 'social atoms' following simple rules may lead to unproductive tendencies. The sentence, however, emphasizes the discovery of certain characteristics or rules, and the term "unproductive tendencies" does not capture the essence of the analogy to the laws of physics.
C. lawlike regulations: This choice fits well with the context of the sentence that talks about viewing people as 'social atoms' and discovering certain characteristics or rules. Describing these rules as "lawlike regulations" aligns with the analogy to the laws of physics. It suggests that there are predictable patterns or regulations governing social behavior.

Blank (ii):
D. inflexible: The sentence describes the movements as "initially chaotic," suggesting a lack of order and flexibility. Describing the movements as "inflexible" contradicts the idea of chaos and disorder, making this option less suitable for the context.
E. straightforward: The sentence describes the movements as "initially chaotic," indicating a lack of order and complexity. Describing the movements as "straightforward" contradicts the idea of chaos and does not align with the context of the sentence.
F. chaotic: The sentence mentions the emergence of channels when people move in crowds, and it describes the movements as "initially chaotic." "Chaotic" means in a state of complete confusion and disorder, which fits the idea that initially, the movements lack order and follow no clear pattern.

Blank (iii):
G. self-defeating: This option suggests that the particular channels become self-defeating, implying that they undermine their own purpose. The sentence, however, talks about the channels becoming self-sustaining and continuing, which is not consistent with the idea of being self-defeating.
H. self-aggrandizing: This choice implies that the channels become self-aggrandizing, meaning they enhance their own importance. The sentence, however, emphasizes the self-perpetuating nature of the channels, not their self-aggrandizement.
I. self-perpetuating: The sentence talks about the emergence of streams of movement as more people join in, creating a pull for others to join the flow. Describing the channels as "self-perpetuating" suggests that once the movement starts, it sustains and continues on its own, reinforcing itself. This choice aligns with the idea that the channels become self-sustaining as more people join the flow.