A cylindrical tank has a base with a circumference of meters and an isosceles right triangle painted on the interior side of the base. A grain of sand is dropped into the tank and has an equal probability of landing on any particular point on the base. If the probability of the grain of sand landing on the portion of the base outside the triangle is 3/4, which of the following is the length of at least one side of the triangle?
a. 3
b. 12
c. under root 2
d. under root 3
e. under root 6