Full question:
Upper H upper C l plus upper N a upper O upper H right arrow upper H subscript 2 upper O plus upper n a upper C l.
Superscript 235 subscript 92 upper U plus superscript 1 subscript 0 n right arrow superscript 90 subscript 38 upper S r plus superscript 143 subscript 54 upper X e plus 3 superscript 1 subscript 0 n.
Superscript 90 subscript 38 upper S r plus superscript 143 subscript 54 upper X e plus 3 superscript 1 subscript 0 n right arrow superscript 235 subscript 92 upper U plus superscript 1 subscript 0 n.
Upper C subscript 10 upper h subscript 8 plus 12 upper O subscript 2 right arrow 10 upper C upper O subscript 2 plus 4 upper H subscript 2 upper O.
Out of these options, the 2nd one (B) is the type that occurs in a nuclear reactor core.