Five jumbled up sentences, related to a topic, are given below. Four of them can be put together to form a coherent paragraph. Identify the odd one out and key in the number of the sentence as your answer:

1. There is a dark side to academic research, especially in India, and at its centre is the phenomenon of predatory journals.

2. But in truth, as long as you pay, you can get anything published.

3. In look and feel thus, they are exactly like any reputed journal.

4. They claim to be indexed in the most influential databases, say they possess editorial boards that comprise top scientists and researchers, and claim to have a rigorous peer-review structure.

5. But a large section of researchers and scientists across the world are at the receiving end of nothing short of an academic publishing scam.