What Is the Major Difference Between Mariner 10 and MESSENGER

Multiple Choice

What is the major difference between Mariner 10 and MESSENGER?

A) Mariner 10 flew past Mercury several times. MESSENGER went into orbit around the planet.
B) MESSENGER made a soft landing on Mercury, but Mariner 10 only flew by.
C) The two spacecraft were essentially identical, except that Mariner 10 landed on the daylight side of the planet and MESSENGER landed on the night side.
D) Mariner 10 was a failed mission. It crashed into Mercury. MESSENGER conducted a successful flyby.