Good Data Sufficiency question. The key concept here is subset constraints in overlapping sets.
The question: among 100 diplomats (A=80, F=85, S=95, E=85), do at least 60 speak all four languages?
Without any constraints, the lower bound from inclusion-exclusion is 80+85+95+85 - 3x100 = 45. So baseline, at least 45 speak all four. Not enough to answer yes or no to the 60 threshold.
Statement (1): A is a subset of E, and E is a subset of S. This tells us all 80 Arabic speakers also speak English, and all 85 English speakers also speak Spanish. So E and S are effectively merged for the English-speaking group - all 85 English speakers also speak Spanish.
Now for French: 85 French speakers. The minimum overlap between the English-speaking group (which is 85 people who all also speak Spanish) and the French group is: 85 + 85 - 100 = 70.
So at least 70 diplomats speak English, Spanish, AND French. Of those 70, what's the minimum who also speak Arabic? 80 Arabic speakers are all inside that E-group of 85. Min overlap of Arabic with that group of at least 70 F-speakers: 80 + 70 - 85 = 65.
Wait, let me be cleaner. We know all 80 Arabic speakers speak E and S. So 80 people speak A+E+S. Min of those 80 who also speak French: 80 + 85 - 100 = 65.
At minimum 65 speak all four. 65 ≥ 60. Answer is YES. Statement (1) alone is sufficient.
Statement (2): 10 diplomats speak only Spanish. So 85 speak Spanish plus at least one other language. This doesn't constrain the four-way overlap enough. We could construct scenarios where the all-four overlap is 45 (below 60) or 80 (above 60). Not sufficient.
Answer: A.
The trap is assuming Statement (1) is complicated to work with because of the chain of subsets. It's actually the opposite - chains make the math cleaner.