What is the difference between mechanical and chemical weathering?

Mechanical weathering breaks rocks into smaller pieces without changing their composition and chemical weathering breaks down rocks by forming new minerals that are stable at the Earth's surface.

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

the answer would be..

b. sucking