1. Condition for interference maxima in YDSE

   In Young's double-slit experiment, bright fringes (maxima) occur when the path difference satisfies $d\sin\theta = n\lambda$ where:

   • $d$ = slit separation
   • $\lambda$ = wavelength
   • $n$ = order of maximum ($0, \pm 1, \pm 2, \dots$)

2. Given data

   The slit separation is twice the wavelength: $d = 2\lambda$

   Substituting into the maxima condition: $2\lambda \sin\theta = n\lambda$ $2\sin\theta = n$ $\sin\theta = \frac{n}{2}$

3. Possible values of $n$

   Since $\sin\theta$ must satisfy $-1 \le \sin\theta \le 1$ we must have $-1 \le \frac{n}{2} \le 1$ $-2 \le n \le 2$

   Thus the allowed integer values of $n$ are: $n = -2, -1, 0, 1, 2$

4. Count the maxima

   These correspond to:

   • second order on one side: $n=-2$
   • first order on one side: $n=-1$
   • central maximum: $n=0$
   • first order on the other side: $n=1$
   • second order on the other side: $n=2$

   So total number of possible maxima is $5$

5. Check options

   • A: three $\to$ incorrect
   • B: five $\to$ correct
   • C: infinite $\to$ incorrect
   • D: zero $\to$ incorrect

Final Answer: $\boxed{\text{B: five}}$