Words given on the left side of (::) are related with each other by some Logic/Rule /Relation. Select the missing word/word pair on the right side of (::) from the given alternatives based on the same Logic/Rule/Relation.

Grip : Spanner :: Amplify : ?

Loudspeaker

Grip : Spanner :: Amplify : ?

The logic followed here is :

The second word is a instrument or device which is used to perform the First word

As

Grip : Spanner

Spanner is the device which is used to provide Grip

Similarly

Amplify : ?

Loudspeaker is the device which is used to amplify the Sound