Mark inherited $25,000 and invested part of it in a money market account, part in municipal bonds, and part in a mutual fund. After one year, he received a total of $1,620 in simple interest from the three investments. The money market paid 6% annually, the bonds paid 7% annually, and the mutually fund paid 8% annually. There was $6,000 more invested in the bonds than the mutual funds. Find the amount Mark invested in each category.

A) x= 2 y= -1 z= 3
B) x= $15,000 y= $8,000 z= $2,000
C) x= -3 y= 5 z= 2