Write the Specified Quantity as a Function of the Specified $A = \frac { \sqrt { 15 } } { 4 } b ^ { 2 }$

Write the specified quantity as a function of the specified variable.
-The base of an isosceles triangle is a fourth as long as the two equal sides. Write the area of the triangle as a function of the length of the base.

A) $A = \frac { \sqrt { 15 } } { 4 } b ^ { 2 }$
B) $A = \frac { 63 } { 8 } b ^ { 3 }$
C) $A = 2 b ^ { 2 }$
D) $A = \frac { 3 \sqrt { 7 } } { 4 } b ^ { 2 }$