The correct answer is $\boxed{\text{B) 0.7}}$.
The ratio of end span length to intermediate span length for a continuous floor slab supported on beams is typically 0.7. This means that the end spans are 70% of the length of the intermediate spans. This ratio is used to ensure that the slab is evenly loaded and that there is no excessive deflection at the ends of the spans.
If the ratio of end span length to intermediate span length is too small, the ends of the slab will be over-loaded and will deflect excessively. This can lead to cracking and other damage to the slab. If the ratio of end span length to intermediate span length is too large, the intermediate spans will be under-loaded and will not be as stiff as they could be. This can lead to problems with vibration and deflection.
The ratio of end span length to intermediate span length is just one of many factors that need to be considered when designing a continuous floor slab. Other factors include the load on the slab, the type of concrete used, and the size and spacing of the beams.