Answer: c. equity strategic alliance
Step-by-step explanation:
This occurs when there is a cross or partial alliance between two organizations, that is when a company buys minor equity in another company (partial equity) or they both buy equity in one another's. (cross equity)
An example us between DoComo holdings and Basic Inc as stated in the question, another example is between Tesla and panasonic which started as a $30million investment.
Equity alliance can either be partial or cross equity alliance.