You Are Using a Telescope with a Diameter of 20

You are using a telescope with a diameter of 20 cm, and you are observing with light of wavelength 650 nm. You are looking at the word "astronomy" on a distant signboard. What maximum angular spacing (in arcseconds) between adjacent letters will ensure that the entire word can be seen clearly?

A) 0.25 arcsec
B) 0.50 arcsec
C) 0.75 arcsec
D) 1.00 arcsec