The correct answer is option 1: Change in its price. A movement along the demand curve of a commodity occurs when there is a change in the price of the commodity itself.

When the price of a commodity increases, consumers typically demand less of it, as it becomes more expensive relative to other goods and services. This leads to a movement upwards and to the left along the demand curve. Conversely, when the price of a commodity decreases, consumers are likely to demand more of it, as it becomes more affordable. This results in a movement downwards and to the right along the demand curve.

It`s important to note that the other options provided may also influence demand, but they do not directly lead to a movement along the demand curve. For example, a change in the price of other commodities (option 2) may affect the relative prices of goods and shift the entire demand curve. Similarly, a change in consumer income (option 3) and changes in tastes and preferences (option 4) can also shift the demand curve.