Select the description(s) that result in a ragged 2-d (matrix) array instantiation.
(this means that directly after the described instantiation, the matrix will be a ragged array with some row lengths being different from other row lengths in the matrix, not a matrix in which all the row lengths in are the same.)
a. a numpy 2-d array whose shape is described by a tuple, like (4, 8) or (3, 4), passed to the constructor.
b. a python list-of-lists in which not all of the inner lists are the same length.
c. a python list-of-lists in which all of the inner lists are the same length.
d. a numpy 1-d array whose individual elements point to separate numpy 1-d arrays (each of which might be a different length).