Final answer:
Jesus is the one who presented himself and gave many convincing proofs that he was alive after his crucifixion, as claimed by his followers.
Step-by-step explanation:
The individual who presented himself and gave many convincing proofs that he was alive is a) Jesus. After his crucifixion, Jesus' followers claim that he rose from the grave after three days. This event is a cornerstone of the Christian faith. The apostles and disciples of Jesus were key in spreading his teachings and message after his resurrection, referring to him as "the Christ" which means "the anointed one" or "savior". It was through these acts and their testimonies that early Christianity began to take shape and expand beyond the immediate circle of Jesus' followers.