You are implementing an ASP.NET AJAX page.
You add two UpdatePanel controls named pnlA and pnlB. pnlA contains an UpdatePanel control named
pnlAInner in its content template.
You have the following requirements.
Update panels pnlA and pnlB must refresh their content only when controls that they contain cause a
postback.
Update panel pnlAInner must refresh its content when controls in either pnlA or pnlB or pnlAInner cause a
postback.
You need to configure the panels to meet the requirements.
What should you do?

A.
Set the UpdateMode of pnlA and pnlB to Conditional. Set the UpdateMode of pnlAInner to Always.

B.
Set the UpdateMode of pnlA and pnlB to Conditional. Set the UpdateMode of pnlAInner to Conditional, and
add AsyncPostBackTrigger elements to its Triggers element for every control in pnlA.

C.
Set the UpdateMode of pnlA and pnlB to Always. Set the UpdateMode of pnlAInner to Conditional.

D.
Set the UpdateMode of pnlA and pnlB to Always. Set the UpdateMode of pnlAInner to Always, and add
AsyncPostBackTrigger elements to its Triggers element for every control in pnlB.