If F is a dimensionless factor, the defection in rigid plate of radius a is__________

• A. \(∆=\frac{pa}{E} 1.5F\)
• B. \(∆=\frac{pa}{E} 1.18F\)
• C. \(∆=\frac{a^2}{2E} 1.18F\)
• D. \(∆=\frac{pa}{E} 2F\)