Human relations are universal, but those defined as basic or primary are:

most "experts" say a.

I would agree with a.

b. defined differently in different cultures

Explanation:
Human relations refer to the ways in which people interact with and relate to one another. While there are universal aspects to human relations, such as the need for communication and social connection, the specific definitions and norms surrounding these relationships can vary across different cultures.

For example, the concept of family and the roles and expectations within a family unit can differ greatly from culture to culture. In some cultures, the extended family plays a central role, and filial piety (respect for one's elders) is highly valued. In contrast, in other cultures, the nuclear family is emphasized, and individualism may be prioritized over familial obligations.

Similarly, the importance placed on hierarchy and authority, the norms for expressing emotions, and the customs relating to friendship, dating, and marriage can all vary between cultures. These cultural variations in defining and prioritizing basic or primary human relations are influenced by a range of factors, including history, religion, values, and social structures.

To understand the specific definitions of basic or primary human relations in different cultures, it is important to study and explore the cultural norms, traditions, and values of those societies. This can be done through research, cross-cultural studies, engaging with people from different backgrounds, and learning from cultural experts or anthropological resources.