今年寒假，你将作为一名交换生去美国待一个月，但家里的小猫没有人照料。现在请你给你的朋友Tony 留个短信，请他记得帮忙照顾这只猫。

Dear Tony,

     I am going to the USA in the _____1_____vacation. I will stay there as an _____2_____ student

for one month. Could you please _____3_____after my pet cat?He's very beautiful and cute.  Please

remember to _____4_____ him three times a day and clean his bed .  Take him _____5_____ a walk

if you have time.  I will bring you beautiful gifts when I come back. See you next month!

                                                                                                                                         Thanks,

                                                                                                                                          Lucy

在某色盲男孩的父母、祖父母、外祖父母中，除祖父是色盲外，其他人色觉均正常，这个男孩的色盲基因来自（）

A.祖父

B.祖母

C.外祖父

D.外祖母