TOEFL Reading: ETS-TOEFL阅读机经 - R176W56RJPRW1V3QL$

According to paragraph 4, what reason has been suggested for why female juncos often migrate farther south than do male juncos? A. To avoid the colder temperatures farther north B. To provide safer habitats for their juveniles C. To avoid having to compete with males D. To find habitats having the longest days