What are the values of the following expressions? You may assume that:

String s $=$ "Hello";

String t $=$ "World";

Group of answer choices

s$.$length$()+$ t$.$length$()$

$[$ Choose $]$

s$.$substring$(1,2)$

$[$ Choose $]$

t$.$charAt$(3)$

$[$ Choose $]$

s $+$ t

$[$ Choose $]$