Explanation

(c) (i) A body having constant speed can have varying velocity as direction may change.
(ii) Position-time graphs for two objects with zero relative velocity are parallel.
(iii) For a given time interval,
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ Distance\ \geq |\ displacement\ |$
$\therefore Average\ speed\ \geq |\ average\ velocity\ |$
Therefore, all the options are true.