pay off properties or use money to buy more?

[Fred Damali]

My goals are to own enough real estate property that can produce 100k a year after all expenses and after having paid the ALL OFF. This will facilitate early retirement.
I am in mid 20's, and have 160k salary. I am paying a loan for my 1st rental property (3-unit house). The rent income pretty much pays for the property with little money coming from me everynow and then to pay any difference.
I have 100k cash and I want to keep buying more rental properties to reach my goal. I am currently looking at a 200k property (3-unit house).
I wonder if its wiser to
A) just finish paying off my 1st property and then getting a 2nd later
B) use that money to make a big downpayement for a 2nd property
c) get (2) 200K rental properties and put down 50k as a downpayment for each.
d)buy a single-family house CASH paid in full.And probably make $1000 month in rent and then use this INCOME to either help pay off my 1st prop mortage or to buy a third property later.