Help me pick between two choice for terms on my upcoming purchase

[Eric Hathway]

I am buying an 11 unit apartment building with a commercial mortgage and have the two following financing options:

 (Both are 20% down, amortizing over 20 years). Purchase price $640,000

A)    4.25%, adjusting every 5 years

or

B)    4.625%, fixed for the first 7, then adjusts every 5 years

Please briefly explain your choice and thank you in advance!!