Final answer:
The muscle fiber type meant for endurance activities, with abundant myoglobin and capillaries but slower and less forceful contractions, is Type I (slow-twitch) fibers.
Step-by-step explanation:
The skeletal muscle fiber type that is designed for endurance with large amounts of myoglobin, many capillaries, and a weak contraction velocity is a) Type I (slow-twitch) fibers.
Type I fibers, also known as slow oxidative or 'red' muscle fibers, are dense with capillaries and rich in mitochondria and myoglobin. Myoglobin gives muscle tissue its characteristic red color and helps in oxygen storage for muscle activity. These fibers can carry a lot of oxygen and are built for sustained aerobic activity, such as that needed in endurance events like marathons. Despite their high endurance, they contract at a slower rate and with weaker force compared to fast-twitch fibers.