a) &
b) >
c) +
d) @

Answer: b
Explanation: Reserved characters are ‘@’, ‘=’, ‘?’, ‘:’, ‘;’, ‘/’, ‘,’, ‘+’, ‘$’, ‘&’. Unsafe characters are space, ‘”’, ‘>’, ‘<’, ‘#’, ‘%’, ‘{‘, ‘}’, ‘~’, ‘^’, ‘[‘, ‘|’, ‘\’, ‘`’, ‘]’. There is a URL Encode for all of these characters. Apart from URL Encode there is Decimal and Hex value also for the characters.