In “Here’s $100 to make sure” MAKE SURE is closest in meaning to: 
According to the previous text, judge the following items.
The word ‘changing’ (l.13) conveys the idea that threats are constantly evolving.
Among the many tasks, mentioned in the third paragraph, a police officer may perform in the line of duty, is to “secure evidence”. The phrase means, in Portuguese, the same as 
No trecho do último parágrafo – Police officers must be available for shift work at any time of day and any day of the week, including holidays. –, a palavra em destaque transmite a ideia de 
The action involved in “to get around a problem” is to: 
The lexical item ´handy´ is used in “Here´s a handy list” (line 4) and “keep it handy” (line 26). In each instance it means respectively: 
The only alternative below which in the text conveys the meaning of ´manner´is: 
In the fragments of the text: “they may lose the desire to master whatever task you are asking them to do” (lines 12-13) and “then you have to do more than just present lessons in the app” (lines 18-19), the verb forms in bold express the ideas, respectively, of 
In the sentence of the text: “However, if you want people to continue using the app, and use it frequently and often, then you have to do more than just present lessons in the app” (lines 17-19), the connector However can be replaced, without any change in meaning, by 
The expression indie workers, found in lines 10 and 90, refers to
