在下列生产函数中,哪个生产函数是规模收益递增的(A)。
①
<imgwidth="150"height="38"src="http://wljy.whut.edu.cn:80/uploadfiles/word/QYJJF.files/QYJJF5695.png">
②
<imgwidth="153"height="34"src="http://wljy.whut.edu.cn:80/uploadfiles/word/QYJJF.files/QYJJF5817.png">
③
<imgwidth="134"height="38"src="http://wljy.whut.edu.cn:80/uploadfiles/word/QYJJF.files/QYJJF5920.png">
④
<imgwidth="175"height="44"src="http://wljy.whut.edu.cn:80/uploadfiles/word/QYJJF.files/QYJJF6043.png">