Jupiter
Retrograde motion.
Jupiter is not the slowest, but it is a lot slower than Earth. Jupiter is the fifth planet from the Sun. The time taken for a planet to orbit the Sun increases with distance from the Sun. There are two reasons : 1) The size of its orbit gets bigger. 2) The planet moves more slowly. This follows from the mathematics of Newton's gravitation theory.
a planet DA
That planet will move faster in its orbit.
mars
All of them.
The planet that has the slowest orbit would be Neptune due to the fact that is is furthest away from the sun. However, if you want to count dwarf planets, then Eris would be the slowest.
pluto... :)
Jupiter
Jupiter
it moves very slowly
A slug moves slowly and so does a snail
A planet's predominant movement (NOT the daily movement related to Earth's rotation, but the apparent movement compared to the background stars) is from west to east. If a planet moves in this direction it is said to be "prograde", if it moves in the opposite direction, it is said to be "retrograde".
Retrograde motion.
Slowly. Their tinly little fins will flap like crazy, but the seahorse will move slowly through the water.
Of the major planets, Neptune. The speed of planets in their orbits is directly related to their distance from the sun. The farther a planet is from the Sun, the slower its orbital speed.