Final answer:
Streamer colors for automatic parachutes with a .75 second time delay cartridge vary, but bright colors like yellow or red are common for visibility. Specifics can be found in manuals or manufacturer's specifications.
Step-by-step explanation:
The color of the streamer attached to an automatic parachute with a .75 second time delay cartridge is usually specific to the parachute manufacturer's design. However, the most common convention is to use a yellow or red streamer for parachutes with emergency or reserve chutes, as these vibrant colors provide high visibility. For such specialized equipment as automatic activation devices used in parachuting, details regarding streamer color and associated time delays would typically be found in the parachute riggers' manual or the manufacturer's specifications.