Consider the following phenomena :
(i) Forest fire (ii) Growth of plants (iii) Low and high tides (iv) Occurrence of a rainbow (v) Earthquakes (vi) Opening of a morning glory flower
Which of the above phenomena can be classified as periodic changes?

Options

A. (i), (ii) and (iii) only
B. (i), (ii) and (v) only
C. (iv), (v) and (vi) only
D. (iii) and (vi) only

Explanation

To determine which of the given phenomena can be classified as periodic changes, we need to analyze each one based on the definition of periodic changes. Periodic changes are those that occur at regular intervals of time.

### Step-by-Step Solution:

1. **Identify the phenomena**: We have the following phenomena to consider:
- (i) Forest fire
- (ii) Growth of plants
- (iii) Low and high tides
- (iv) Occurrence of a rainbow
- (v) Earthquakes
- (vi) Opening of a morning glory flower

2. **Analyze each phenomenon**:
- **Forest fire**: This is not a periodic change as it does not occur at regular intervals. It can happen due to various factors and is unpredictable.
- **Growth of plants**: While plants grow, this process does not occur at a fixed interval. It depends on various environmental factors, so it is not classified as periodic.
- **Low and high tides**: This is a clear example of a periodic change. Tides occur regularly due to the gravitational pull of the moon and the sun, following a predictable cycle.
- **Occurrence of a rainbow**: Rainbows occur under specific conditions (rain and sunlight) but do not happen at regular intervals, so they are not periodic.
- **Earthquakes**: These are sudden and unpredictable events that do not follow a regular time pattern, thus they are not periodic.
- **Opening of a morning glory flower**: This occurs at specific times of the day (usually in the morning), making it a periodic change.

3. **Conclusion**: Based on the analysis:
- The phenomena that can be classified as periodic changes are:
- (iii) Low and high tides
- (vi) Opening of a morning glory flower

### Final Answer:
The periodic changes from the given phenomena are:
- Low and high tides
- Opening of a morning glory flower