The system releases hormones into the bloodstream to regulate cellular use of absorbed nutrients.

The endocrine system releases hormones into the bloodstream to regulate cellular use of absorbed nutrients. The endocrine system is made up of glands that produce and secrete hormones, chemical substances produced in the body that regulate the activity of cells or organs. Hormones regulates the body's growth, metabolism, growth and development, tissue function, sexual function, reproduction, among other functions. 

Nimbostratus is the correct answer.
explanation: nimbostratus clouds are the type of clouds that are mostly likely present on gray, rainy day. these clouds produce continuous rain, snow and there is no thundering or lightening either.