The sentences given below, when properly sequenced, form a coherent paragraph. Each sentence is labelled with a number. Decide on the most logical order and enter the sequence of numbers in the space provided.

1. In drought conditions, water often depletes in the topsoil and remains accessible only in the deeper subsoil layers.

2. A new study gives new insights into how the acid changes root growth angles to enable plants to reach out deeper subsoils in search of water.

3. Plants rely on their root systems, the primary organs for interacting with soil, to actively seek water.

4. Abscisic acid plays an important role in helping plants adapt to these challenging conditions.

The passage discusses how plants adapt to drought conditions by modifying their root growth patterns through certain chemical signals.

Statement 1 talks about the situation when, due to droughts, the water depletes at the topsoil, and Statement 4 gives us a solution as to what plants do to adapt to "these challenging conditions"( using a certain acid). 14, therefore, becomes a logical pair. Statement 2 further provides concrete evidence of HOW the acid (mentioned in 4) enables deeper water access, completing the narrative. SO the sequence should follow 142. 

Statement 3 introduces the general topic of plants using their root systems to seek water. This is the natural starting point, and not a conclusion, as it establishes the basic biological context. So the correct sequence should be 3142.