ABC Inc Purchased Shares of DEF Inc as Follows

ABC Inc purchased shares of DEF Inc as follows:

June 30^th, 2013 4,000 shares @ $3 per share $12,000
June 30^th, 2014 3,000 shares @ $4 per share $12,000
June 30^th, 2015 3,000 shares @ $6 per share $18,000

The shares are considered to be passive investments. ABC Inc. has a December 31^st, year-end.
The market value of the DEF shares at each year-end was as follows:
December 31^st, 2013 $3.50 per share
December 31^st, 2014 $5.00 per share
December 31^st, 2015 $5.50 per share
On July 1^st, 2015, ABC sold half its shares in DEF Inc. for $6.50 per share.

-When a company holds between 20% and 50% of the outstanding shares of an investee, which of the following statements applies:

A) The investor should always use the equity method to account for its investment
B) The investor should use the equity method to account for its investment unless circumstances indicate that it is unable to exercise significant influence over the investee.
C) The investor must use the cost method unless it can clearly demonstrate the ability to exercise significant influence over the investee
D) The investor should always use the cost method to account for its investment