Which statement is true about variables in JavaScript?

What will be the output of the following code?

let a = 1; let b = 2; let c = a + b; console.log(c);

A). 12

B). 12

C). 3

D). NaN

Which of the following is NOT a valid variable name in JavaScript?

A). myVar

B). $myVar

C). _myVar

D). 123myVar

Can variables declared with 'var' be redeclared in the same scope?

A). Yes

B). No

C). Only inside a function

D). Only inside a loop

Can you reassign a value to a variable declared with let?

A). Yes

B). No

C). Only in strict mode

D). Only inside a block

What will be the output of the following code?

let x; console.log(x);

A). null

B). undefined

C). 0

D). NaN

What will be the output of the following code?

const a = 10; a = 20; console.log(a);

A). 10

B). 20

C). Error

D). undefined

What is hoisting in JavaScript?

A). Function call before declaration

B). Variable declared at the top

C). Variable and function declaration are moved to the top

D). Variable scope

Which keyword should be used to declare a block-scoped variable?

A). var

B). let

C). const

D). Both let and const

What will be the output of the following code?

console.log(a); var a = 10;

A). 10

B). undefined

C). Error

D). null

Which of the following is true about 'const' variables in JavaScript?

A). They can be redeclared

B). They cannot be reassigned

C). They can be reassigned

D). They are always undefined