Given a transaction database for mining association rule as follows:

TID Items

100 A C D

200 B C E

300 A B C E

400 B E

For given support count = 2, which one of the following item-sets is not a frequent item-set?

a. {B, C, E}

b. {B, E}

c. {C, E}

d. {A, C, D}