What did Europeans, africans and Americans trade as a result for the Colombian exchange A. Railroad engineering ideas

B. Computer technology

C. Film production techniques

D. Agricultural knowledge

Also under the subject I meant to put social studies not physics.

Agalvanometer has an internal resistance of 100 ω and deflects full-scale at 2.00 ma. what size resistor should be added to the galvanometer to convert it to a milliammeter capable of reading up to 4.00 ma, and how should this resistor be connected to the galvanometer?

In an experiment, how can i change human errors? be specific.

When using the scientist method, which step comes last?