Four words can be packed into 64-bit by using the data type,
(a) unpacked word
(b) packed word
(c) packed doubled word
(d) one quad word
I had been asked this question in an international level competition.
Question is taken from MMX Data Types, Wrap-around and Saturation Arithmetic, Multimedia Application Programming, Pentium III (P-III) CPU in chapter Recent Advancements in Microprocessor Architecture of Microprocessor