To solve this question, the user needs to know about planetary transits and their occurrence.

A transit is a phenomenon that occurs when one celestial body appears to move across the face of a larger, more distant body. In the context of this question, the user needs to know which planet recently transited the sun after a gap of 122 years.

Now, let's go through each option and explain why it is right or wrong:

A. Mars: Mars is not the correct answer. While Mars does transit the sun, its most recent transit occurred in 2019, which is not a gap of 122 years.

B. Venus: This is the correct answer. Venus recently transited the sun on June 6, 2012. The previous transit of Venus occurred in 1882, which was 122 years before the 2012 transit.

C. Jupiter: Jupiter does not transit the sun as often compared to Venus and Mercury. There is no recent transit of Jupiter that occurred after a gap of 122 years.

D. Saturn: Saturn does not transit the sun as often compared to Venus and Mercury. There is no recent transit of Saturn that occurred after a gap of 122 years.

Therefore, the answer is: B. Venus