Many pilots would define Va as something along the lines of " The speed at which the aircraft will stall at its limiting load factor" or " The maximum speed at which full control deflection can be carried out without exceeding the limiting load factor". But neither of these definitions are correct.
The following material is taken from a FAA discussions following the loss of the A300 fin over new York.
Quote:
Code of Federal Regulations Sec. 23.1507Part 23 AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES
Subpart G--Operating Limitations and Information
Sec. 23.1507[Operating] maneuvering speed.[The maximum operating maneuvering speed, VO, must be established as an operating limitation. VO is a selected speed that is not greater than established in Sec. 23.335(c).]Amdt. 23-45, Eff. 09/07/93 Comments Document HistoryNotice of
Proposed Rulemaking Actions:Notice of Proposed Rulemaking. Notice No. 90-18; Issued on 06/15/90.Final Rule Actions:Final Rule. Docket No. 26269; Issued on 07/28/93.
The following text is extracted from the above document.
Reference: Conference proposals 119 and 120.
No action is being taken to amend Section 23.335 Design airspeeds.
Quote:
Explanation: Conference proposal 187 recommends revision of Section 23.335(c) to increase the design load factor to account for possible overloads resulting from maximum airplane maneuvers at speeds greater than VS√n for cases where the applicant chooses a design maneuvering speed greater than V=VS√n as allowed by Section 23.335(c). In support of conference proposal 187, the submitter states that the purpose of maneuvering speed (in addition to supplying a speed for design of control surfaces in accordance with Sections 23.423, 23.441 and 23.445) is to provide an operating speed where a pilot can be assured of not exceeding the design limits during maneuvers. If a design maneuvering speed in excess of VS√n is chosen (as currently allowed by Section 23.335(c)), and if the airplane is operated at that speed during maneuver, the potential exists for a pilot to exceed the design limit load factor unless that load factor is increased accordingly.
Post conference review indicates that the design maneuvering speed criteria provided in Section 23.335 is necessary and sufficient for control surface design. As such, design maneuvering speed selections greater than VS√n are appropriate, and requiring increases in load factor above those specified in Section 23.337 are unjustified.
However, the FAA recognizes that maneuvering speed is also used by the pilot as that airspeed below which full control surface inputs can be accomplished without structural damage. Maneuvering speed may also be used as a gust penetration speed to minimize the possibility of airframe damage. If the airplane is maneuvered at its maximum weight at airspeeds less than VS√n the airplane will stall prior to exceeding the maximum design load factor. If the airplane is operated at speeds greater than VS√n in the same conditions, the maximum design load factor can be exceeded.
So a single full deflection of the pitch control at exactly Va will not damage flight controls, but it may damage the aircraft structure, if the aircraft designers have selected a value of Va that is higher than the minimum permitted.
So option b in the OP's question may or may not be correct.
More discussion of the subject can be found at the link below.
http://forums.jetcareers.com/threads...-to-you.94018/