Final answer:
The correct answer is option a) In Capernaum.
Step-by-step explanation:
In the Gospel of Mark, Jesus' ministry begins not in Capernaum, Nazareth, Bethlehem, or Jerusalem directly, but His public ministry is notably established after His baptism by John the Baptist. The first active phase of His mission, however, where He starts teaching and gathering His disciples, is indeed in the city of Capernaum. This is described in Mark 1:21-28, signifying the start of His public work. In summary, option (a) Capernaum is the correct answer to where Jesus' ministry started in the Gospel of Mark.
The city of Jerusalem is of immense importance to Christians due to various key events in Jesus' life. Crucially, it is the location of the Holy Sepulchre, which is the site believed to be where Jesus was crucified and resurrected. This makes the Holy Sepulchre the correct answer among the options, highlighting its profound importance to Christian faith and therefore making option (a) the right answer regarding the site of particular importance to Christians in Jerusalem.