Consider a random variable that can take values {1, 2, 3, 4, 5, 6, 7} with probabilities 0.1, 0.1, 0.15, 0.15, 0.15, 0.15, 0.2. How many bits, on average, will be required to encode this source using a Huffman code?
a) 2.500 bits
b) 2.771 bits
c) 2.800 bits
d) 3.771 bits