Will an increase or decrease in osmolarity stimulate ADH?
Recall ADH is released in response to decreased blood volume or changes in osmolarity for the purpose of promoting water retention.
Therefore, an increase in osmolarity (higher salt content, less fluid) would increase ADH because the blood would be more concentrated.
For example, think of it in terms of exercising. When you exercise, you sweat and therefore you lose overall body fluid. Therefore, there will be less blood volume which makes what blood you have more concentrated (ie an increase in osmolarity). Therefore, ADH would be stimulated to act on kidneys to promote the retention of water.