Here's what the stem tells us:
In response to alarming increase in pickpocketing at Karlarinda's airport, airport commission posted brightly-colored signs informing travellers to be aware of pickpockets. However, in months after this, the cases of pickpocketing saw a sharp rise. We have to find a reason to explain this paradox. Ideally pickpocketing cases should have reduced due to increased signage. Thus, our option has to explain this discrepancy. Let's look at the options
Option A: Even is 40% of travellers are unable to read the signs due to language differences, the rest 60% still can. This should have overall had a positive impact in reduction of pickpocketing. However, that is not the case. Hence, we can eliminate this option.
Option B: This abolition of sales tax, caused Karlarinda to be a luxury shopping destination 7 years ago. While this would increase the number of people carrying good amounts of money with them and hence the airport becoming a hotspot for pickpocketing, this was something that happened 7 years ago. The effect of this should have been gradual. Also it would have meant that even last year it was also a luxury shopping destination. Hence, there was not a big difference in the status of Karlarinda as a shopping destination before or after the signages were posted. Hence, this option does not give us any explanation. We can eliminate this.
Option C: This patrolling should have decreased the pickpocketing cases. However, they kept on increasing. Besides, there seems to be no relation between the signage and patrolling. We do not get any explanations on why the discrepancy. We can safely eliminate this option.
Option D: I went for this as my answer. This explains a relation between increased signage and how it caused an increase in pickpocketings. People looking at the signs instinctively checked the pockets where they kept their valuables thereby giving a signal to the pickpockets of where the valuables are located, thereby helping them rob the passengers. This explains the paradox and is our correct choice.
Option E: These belt packs, which are worn under the clothing of a traveller should make it more difficult for pickpockets to rob passengers, hence reducing the overall cases of pickpocketing. However, that is not the case. We can thus, eliminate this option