The correct answer is D. All of the mentioned.
A universal function (ufunc) is a function that operates on multiple arrays at once. It takes array inputs and produces array outputs. Broadcasting is used throughout NumPy to decide how to handle disparately shaped arrays. The output of the ufunc is necessarily an ndarray, if all input arguments are ndarrays.
However, there are some cases where a ufunc can produce a scalar output, even if all input arguments are ndarrays. For example, the sum ufunc will produce a scalar output if all input arguments are 1-dimensional arrays.
Additionally, there are some cases where a ufunc can produce an array output, even if not all input arguments are ndarrays. For example, the where ufunc can produce an array output if one of the input arguments is a boolean array.
Therefore, the statement “The output of the ufunc is necessarily an ndarray, if all input arguments are ndarrays” is not always true.