Answer: social trends
Explanation: In simple words, social trend refers to the activity that is highly participated by the majority of individuals in a society. These trends are part of the external environment of the business.
In the given case, the company is modifying their products as the customers nowadays are more aware and concerned about the environment. Thus, it is trend that majority of society has become Eco-friendly.
From the above we can conclude that the correct option is B.