Which of the following is true?

Select one:

a$.$ The product $"$P$"$ in the marketing mix stands for only physical goods.

b$.$ The product $"$P$"$ in the marketing mix stands for both physical goods and services.

c$.$ The product $"$P$"$ in the marketing mix stands for only tangible merchandise.

d$.$ The product $"$P$"$ in the marketing mix stands for both physical goods and tangible mer