Why were animals such as horses and mammoths an important resource for humans

The correct answer to this open question is the following.

Although you forgot to include the options, we can say the following.

Animals such as horses and mammoths were an important resource for humans in that these animals provided meat for eating and their hair could be used as thread for sewing clothes.

When humans used to hunt to feed their families, mammoths were a great source of food, meat, and protein. From mammoths' skin, humans could make furs that were used as clothes to protect them from harsh weather conditions. When humans domesticated horses, they represented a great resource for transportation and carry relatively heavy loads. So these animals have been useful for human beings.

the answer is prolly b

by 1880, germany had more rail lines than great britain and russia.