The correct answer is option 'D' - Primary sector.

Explanation:
The primary sector refers to the sector of the economy that involves the extraction and production of natural resources, such as agriculture, mining, fishing, and forestry. The tertiary sector refers to the sector that provides services to the consumers, such as retail, banking, healthcare, education, and tourism.

The share of the tertiary sector to the GDP has increased over time due to economic development and the shift towards a more services-oriented economy. This is a common trend observed in many developed and developing countries. As a country progresses and its economy becomes more advanced, the share of the tertiary sector in the GDP tends to increase.

On the other hand, the contribution of the primary sector to employment is still the highest at present. This is because the primary sector is labor-intensive and requires a large workforce for activities such as farming, mining, and fishing. In developing countries, where agriculture is still a significant source of livelihood for a majority of the population, the primary sector continues to be the largest employer.

Even though the share of the tertiary sector in the GDP has increased, it is important to note that the primary sector still plays a crucial role in providing employment opportunities and supporting the livelihoods of a significant portion of the population. The primary sector is also important for ensuring food security and meeting the basic needs of the population.

In conclusion, while the share of the tertiary sector in the GDP has increased, the primary sector continues to provide the highest contribution to employment at present. It is important for policymakers to recognize the significance of the primary sector in terms of employment generation and ensure that appropriate policies and support are provided to promote the growth and development of this sector.