In the previous question, the blocks are allowed to move for some time, after which M is stopped momentarily (brought to rest and released at once). After this,
(a) both blocks will move with the same acceleration
(b) the string will become taut (under tension) again when the blocks acquire the same speed
(c) the string will become taut again when the blocks cover equal distances
(d) at the instant when the string becomes taut again, there may be some exchange of impulse between the string and blocks
