Explanation:

The Indus Valley Civilization, also known as the Harappan Civilization, was one of the earliest urban civilizations in the world, flourishing from around 2500 BCE to 1900 BCE. It was located in the region that is now modern-day Pakistan and northwestern India. The civilization is known for its advanced urban planning, sophisticated drainage systems, and unique artifacts, including seals.

Seals in the Indus Valley Civilization:

The seals found in the Indus Valley Civilization are some of the most distinctive and well-known artifacts from this ancient civilization. These seals were typically made of stone or terracotta and were used for various purposes, including trade, administration, and religious rituals. The seals were intricately carved with different symbols, including animals, humans, and geometric patterns. They were often used to mark goods, containers, or documents.

Types of Seals:

1. Rectangular seals: Rectangular seals were one of the most common types of seals found in the Indus Valley Civilization. They were usually made of steatite, a type of soft stone, and were rectangular in shape. These seals often had symbols or inscriptions carved on them, which were used to identify the owner or the purpose of the seal.

2. Pentagon seals: Pentagon seals, as the name suggests, were seals with a pentagonal shape. While there is limited evidence of pentagon seals from the Indus Valley Civilization, there have been a few rare examples found.

3. Circular seals: Circular seals were another common type of seal found in the Indus Valley Civilization. These seals were typically made of stone or terracotta and were circular in shape. They often had intricate carvings or symbols on them.

4. Cylindrical seals: Cylindrical seals were cylindrical in shape and were made of stone or terracotta. These seals were typically used for sealing containers or jars. They had carvings or inscriptions on the cylindrical surface, which would leave an impression when pressed onto clay or wax.

5. Triangular seals: Triangular seals, as the name suggests, were seals with a triangular shape. These seals were less common compared to rectangular or circular seals, but there have been a few examples found in the Indus Valley Civilization.

6. Semi-circular seals: Semi-circular seals were seals with a semi-circular shape. These seals were less common compared to rectangular or circular seals, but there have been a few examples found in the Indus Valley Civilization.

Seals in the Indus Valley Civilization base:

Based on the information provided, the seals found in the Indus Valley Civilization base include:
- Rectangular seals
- Circular seals
- Cylindrical seals
- Triangular seals

Therefore, the correct answer is option 'A' - 1, 3, 4, and 5.