## Core Concept
The question pertains to pediatric dentistry, specifically the management of a tooth after a pulpectomy procedure. A pulpectomy is performed when the dental pulp is severely infected, and the tooth cannot be saved with a less invasive procedure like a pulpotomy. The ideal material for obturation (filling) of the root canal system after pulpectomy should promote healing, prevent bacterial growth, and be resorbable to accommodate the physiological resorption of the primary tooth roots.

## Why the Correct Answer is Right
The correct answer, **MTA (Mineral Trioxide Aggregate)**, is considered an ideal material for obturation after pulpectomy in primary teeth. MTA promotes healing by providing a conducive environment for the formation of a hard tissue barrier and encourages the resorption of the primary tooth roots. It is also known for its antimicrobial properties, which help prevent infection. Moreover, MTA is biocompatible and can be resorbed, making it suitable for use in primary teeth.

## Why Each Wrong Option is Incorrect
- **Option A:** This option is incorrect because, although not specified, commonly used materials like **Zinc Oxide Eugenol (ZOE)** or **Calcium Hydroxide** have limitations. ZOE can interfere with the polymerization of some restorative materials and has limited antimicrobial properties compared to MTA. Calcium Hydroxide, while used historically, has a higher pH than MTA and may cause damage to the periodontal tissues if extruded beyond the apex.
- **Option B:** Similarly, this option lacks specificity but could refer to other materials like **Resorbable Calcium Phosphate** or **Bioactive Glass**, which, although promising, do not have the same level of clinical evidence supporting their use as MTA in pulpectomy procedures.
- **Option D:** This option could potentially refer to **Gutta Percha**, which is commonly used in root canal fillings for permanent teeth but is not ideal for primary teeth due to its non-resorbable nature.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the material used for obturation after pulpectomy in primary teeth should ideally be resorbable and promote a favorable environment for the successor tooth. MTA stands out as a preferred choice due to its balance of antimicrobial activity, biocompatibility, and resorbability.

## Correct Answer: C. MTA.