Which of the following is right about open-end and closed-end mutual funds? （ ）

A、Closed-endmutualfundsdonotallowwithdrawalsfrominvestorsandthereforecreatedifficultiesformanagers.
B、Open-endmutualfundscanbecomemuchbiggerintermsofthesizeofassetsundermanagementthanitwasinitiallylaunched.
C、Neitheropen-endnorclosed-endmutualfundscanchangetheirportfoliocomponents.
D、Closed-endmutualfundinvestorscangetridoftheirinvestmentbysellingthefundsharestootherinvestors.