What type of forces cause changes in motion?

A. Balanced forces

B. Equal and opposite horizontal forces

C. Equal and opposite vertical forces

D. Unbalanced forces

Plz I need help

Two solids are mixed in a flask and stirred. after a few minutes, the flask becomes cold. which of the following best describes this reaction? a. an exothermic reaction b. a combustion reaction c. an endothermic reaction d. a decomposition reaction