What is the full form of $VNTR$?

$DNA$ fingerprinting was discovered by .........

Read the following statements:
$A.$ Variation at genetic level arises due to mutations.
$B.$ The technique of $DNA$ fingerprinting was initially developed by Alec Jeffreys.

Give scientific reasons: $DNA$ polymorphism is the basis of genetic mapping of human genome.

$A$: Unknown $DNA$ after hybridization with $VNTR$ probe,the autoradiogram gives many bands of differing sizes in $DNA$ profiling.
$R$: These bands represent the $DNA$ fingerprint of the organism.

Suppose $DNA$ samples collected for $DNA$ fingerprinting analysis are less than the required quantity. Which of the following techniques is helpful to make the samples sufficient for above analysis?