Which base class constructor should you use at line 02?

You have a timer job that has the following constructors. (Line numbers are included for reference only.)

01 public TimerJob1 () : base() { }
02 public TimerJob1(SPWebApplication wApp)

You need to ensure that the timer job runs on the first available timer server only.

Which base class constructor should you use at line 02?

A.
public TimerJob1(SPWebApplication wApp) : base
(null, wApp, null, SPJobLockType.ContentDatabase) { }

B.
public TimerJob1(SPWebApplication wApp): base
(null, wApp, null, SPJobLockType.Job){ }

C.
public TimerJob1(SPWebApplication wApp):base
(null, wApp, null, SPJobLockType.None) { }

D.
public TimerJob1(SPWebApplication wApp):base
(“TimerJob1”, wApp, null, SPJobLockType.None) { }

Explanation:
MNEMONIC RULE: “SPJobLockType.Job”

Job member locks the timer job so that it runs only on one machine in the farm.

SPJobLockType Enumeration
http://msdn.microsoft.com/en-us/library/microsoft.sharepoint.administration.spjoblocktype.aspx