14. Which of the following elements can show covalency greater than 4?

(a) Be

(b) P 

(c) S

(d) B

(b, c)
Elements Be and B lie in the 2nd period. They can have a maximum of 8 electrons in the valence shell. In other words, they can have a maximum covalency of 8/2=4.
However, elements P and S have vacant d-orbitals in their respective valence shells and hence can accommodate more than 8 electrons in their respective valence shell. In other words, they can show a covalency of more than 4.