A.T. Robertson Commentary Mark 12:11

"This was from the Lord, And it is marvellous in our eyes?" — Mark 12:11 (ASV)

This (αυτη). Feminine in LXX may refer to

kephal (head) or may be due to the Hebrew original

zoth (this thing) which would be neuter τουτο in a Greek original, a translation Hebraism.