The passage states a circular reference actually
1. if HK is useful to china -> HK remains capitalist
2. If HK is prosperous -> HK is useful to china
3. if HK remains capitalist -> HK is prosperous
replace 2 and 3:
1. if HK is useful to china -> HK remains capitalist if A then B
3. if HK remains capitalist -> HK is prosperous if B then C
2. If HK is prosperous -> HK is useful to china if C then A
this is a circular reference.
Now, that was just some useful point of view to learn I guess.
What can we infer from above logical statements?
1- acc to Modus Tollens, we can expect to have if NOT B then NOT A, or any similar statement in all three
2- because it is a circular reference we can expect to have if A then C. or if B then A, or even if C then C.
Rule 1: Find the conclusion, (which we do not have yet)
Rule 2: Eliminate 4 answers
(A) If Hong Kong fails to stay prosperous, it will no longer remain part of mainland China.
first half goes well "If NOT C then" second half is irrelevant not among A,B or C. eliminate
(B) If Hong Kong retains its capitalist ways until 1997, it will be allowed to do so afterward.
if C , then C. seems promising, lets keep it.
(C) If there is a world economic crisis after 1997, it will not adversely affect the economy of Hong Kong.
clearly irrelevant information. nothing about crisis or its effect on HK. eliminate
(D) Hong Kong will be prosperous after 1997
This is tricky. it will hold true if we know HK is already in the loop. what if it is outside of it? HK must be useful to China (we do not know that) and must have remained capitalist (we do not know that either) so that we can infer that HK will be prosperous. eliminate
(E) The citizens of Hong Kong will have no restrictions placed on them by the government of mainland China.
no info about HK citizens. eliminate.
Only answer remaining : B