Answer:
a. Collective
Step-by-step explanation:
Collective nouns are nouns that are normally in its singular form but that refers to a number of people, animals, things or concepts considered as a single entity because they share one or more characteristic. "Team" is an example of a collective noun because in the sentence it is its singular form and refers to a group of scientists and engineers.
Some other examples of collective nouns are class, herd, flock, gang, mob, group, and family.