All are colourless plastids(leucoplasts) except

The correct option is rhodoplast.

Step-by-step Explanation:

Plastids are membrane-bound organelles found in the cells of plants, algae, and some other eukaryotic organisms. They are categorized based on their pigmentation and function.

1. Understanding Leucoplasts:
Leucoplasts are a category of plastids that lack pigments and are therefore colorless. Their primary function is the storage of food reserves such as starches, lipids, or proteins. They are subclassified depending on what they store:
- Amyloplasts: These store starch.
- Elaioplasts (or Oleoplasts): These store lipids (fats/oils).
- Proteinoplasts (or Aleuroplasts): These store proteins.

Since amyloplasts, elaioplasts, and proteinoplasts are types of leucoplasts, they are all colorless plastids.

2. Analyzing the Rhodoplast:
A rhodoplast is a specialized type of chromatophore or chromoplast found in red algae (Rhodophyta). Rhodoplasts contain photosynthetic pigments such as chlorophyll a, phycobilins (phycoerythrin and phycocyanin), and carotenoids. Phycoerythrin gives red algae and their rhodoplasts a characteristic red color. Therefore, rhodoplasts are colored plastids, not colorless leucoplasts.

Thus, all the given options are colorless plastids except for rhodoplast, which is a colored plastid.