**Core Concept**
The question is related to growth monitoring, which is a crucial aspect of child health and development. Growth monitoring involves tracking a child's growth parameters, such as weight, height, and head circumference, to identify any potential health issues or developmental delays.

**Why the Correct Answer is Right**
The correct answer is **Mid-Upper Arm Circumference (MUAC)**. MUAC is a widely used indicator for growth monitoring, particularly in low-resource settings like Anganwadi centres. It is a simple, non-invasive, and cost-effective method to assess a child's nutritional status and detect malnutrition early. MUAC is measured by wrapping a flexible tape around the mid-point of the child's upper arm, and the reading is compared to a standardized growth chart.

**Why Each Wrong Option is Incorrect**
* **Option A:** Weight-for-age is another important growth parameter, but it is not the specific indicator used for growth monitoring at Anganwadi centres.
* **Option B:** Height-for-age is a measure of a child's growth and development, but it is not the primary indicator used for growth monitoring in this context.
* **Option C:** Head circumference is an important parameter for monitoring growth and development in infants, but it is not the specific indicator used for growth monitoring at Anganwadi centres.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that MUAC is a valid indicator for detecting malnutrition in children, particularly in low-resource settings. A MUAC reading below 11.5 cm is considered a sign of severe acute malnutrition, while a reading between 11.5 cm and 12.5 cm indicates moderate acute malnutrition.

**Correct Answer:** C. MUAC