Step 1: Recall the flexibility matrix method.
The flexibility matrix relates applied forces to the resulting displacements.
Step 2: Identify its alternate name.
Since the unknowns in this method are the redundant forces, it is commonly known as the Force Method.
Hence,
\[
\boxed{\text{Force Method}}
\]
is the correct answer.
Therefore,
\[
\boxed{(A)}
\]
is the correct answer.