'…… in a haphazard way.' The word 'haphazard' means

The word 'haphazard' means lacking order or organization; done in a random or unplanned manner. In the passage, it describes how street learning of language happens without a structured plan. The closest synonym is 'unorganized'. 'Dangerous' refers to risk, 'safe' is the opposite of risk, and 'proper' means correct/appropriate. Hence option (2), unorganized, is correct.