Which rule ensures that a field must not be left empty?

What is the primary purpose of form validation?

A). Enhance visual design

B). Secure data submission

C). Improve page load speed

D). Reduce server requests

How do you specify a custom error message for a validation rule?

A). error: 'Message'

B). message: 'Message'

C). msg: 'Message'

D). messages: { fieldName: 'Message' }

What is the correct way to specify validation rules in the jQuery Validation Plugin?

A). rules: { fieldName: rule }

B). fields: { rule: fieldName }

C). options: { fieldName: rule }

D). validate: { rule: fieldName }

What does the equalTo rule validate?

A). Field value must be unique

B). Field value must be a number

C). Field value must match another field

D). Field value must be an email address

How can you add a custom validation method using the jQuery Validation Plugin?

A). $.validator.custom()

B). $.validator.addMethod()

C). $.validator.newMethod()

D). $.validator.create()

Which jQuery plugin is commonly used for form validation?

A). jQuery UI

B). jQuery Mobile

C). jQuery Validation Plugin

D). jQuery Animate

How do you include the jQuery Validation Plugin in your HTML file?

A). Using a script tag

B). Using a link tag

C). Using an iframe

D). Using an embed tag

How can you make a field optional in jQuery Validation Plugin?

A). By not including it in the rules section

B). By setting the required rule to false

C). By using the optional rule

D). By setting the field type to optional

How do you validate a field that should only contain numbers?

A). Use the number rule

B). Use the digits rule

C). Use the numeric rule

D). Use the integer rule

Which method is used to initialize form validation with the jQuery Validation Plugin?

A). .validate()

B). .check()

C). .verify()

D). .init()