By the first century CE, there is evidence of changes in Buddhist ideas and practices.
Which of the following changes were visible in Buddhism in this context?

All of the above.

By the first century CE, Buddhism underwent changes in its concepts and practices. Initially, early Buddhist teachings stressed the significance of individual effort in attaining nibbana, and the Buddha was revered as a human who achieved enlightenment through personal endeavors. However, over time, the notion of a savior emerged, suggesting someone capable of ensuring salvation.

Concurrently, the idea of the Bodhisattva also evolved. Bodhisattvas were seen as deeply compassionate beings who accumulated merit through their efforts not for their own nibbana and renunciation of the world, but to aid others. Consequently, the worship of images of the Buddha and Bodhisattvas became a prominent aspect of this tradition.

This new way of thinking was termed Mahayana, meaning the "great vehicle." Those who embraced these beliefs referred to the older tradition as Hinayana or the "lesser vehicle."