Events that take place in eutrophication on given below
(a) excessive growth of algae
(b) depletion of dissolved oxygen
(c ) bacteria feed on dead algae cells
(d) aquatic body becomes rich in phosphates
The correct order of events cells that occurs here is

Options

A. (a), (d) , (c ), (b)
B. (d), (a), (c ), (b)
C. (a), (b), (d), (c )
D. (d), (c ), (b), (a)

Answer

To solve the question regarding the events that take place in eutrophication, we will analyze the given options and arrange them in the correct order. Here are the steps to arrive at the solution:

### Step 1: Identify the Events
The events given are:
(a) Excessive growth of algae
(b) Depletion of dissolved oxygen
(c) Bacteria feed on dead algae cells
(d) Aquatic body becomes rich in phosphates

### Step 2: Understand Eutrophication
Eutrophication is a process that occurs when a water body becomes enriched with nutrients (particularly phosphates and nitrates), leading to excessive growth of algae (algal bloom). This process can have several stages.

### Step 3: Establish the Sequence of Events
1. **Aquatic body becomes rich in phosphates (d)**: This is the initial step where nutrients, particularly phosphates, enter the water body from sources like agricultural runoff, sewage, etc. This sets the stage for eutrophication.

2. **Excessive growth of algae (a)**: The increase in phosphates leads to the rapid growth of algae, known as algal bloom. This is the second step in the eutrophication process.

3. **Bacteria feed on dead algae cells (c)**: As the algae die off, bacteria decompose the dead algae. This is the third step in the sequence.

4. **Depletion of dissolved oxygen (b)**: The decomposition process by bacteria consumes a significant amount of dissolved oxygen in the water, leading to hypoxic conditions. This is the final step in the eutrophication process.

### Step 4: Write the Correct Order
Based on the analysis, the correct order of events is:
(d) → (a) → (c) → (b)

### Final Answer:
The correct order of events that occurs in eutrophication is: **D-A-C-B**

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