Answer:
D. both a and b
Explanation:
There are 3 stages to technological change:
1. Invention - this is when new technology is created or invented.
2. Innovation - this is application of new invention
3. Diffusion - diffusion is when knowledge and use of new technology spreads. Training is one of the ways through diffusion can occur. Therefore , training is an example of technological change.
I hope my answer helps you