被子植物比裸子植物更适应陆地生活，分布更广泛，种类更多，其原因是（　　）

①果实可以保护种子免受外界环境不利因素的影响    ②种子更大

③有些果实表面有翅或毛，适于随风传播                ④有些果实颜色鲜艳，有香甜的浆液或果肉，能诱使动物来吃，利于播种．

    BUS SERVICE

    New York City — Brennan, New Jersey

    (Trip time: 30 minutes each way )

    Timetable

    Buses leave the Railway Station, New York 7:00 a.m. and every half-hour thereafter(此后) until 11:30 p.m. (7 days a week).

    Buses leave Brennan Station 20 minutes before and after every hour from 6:20 a.m. to 10:40 p.m. (7 days a week ).

    Evening rush hours(5:00 p.m. to 7:00 p.m.) buses leave the Railway Station, New York every 15 minutes (Monday — Friday).

    Holidays: buses leave every hour on the hour time, each direction.

All tickets must be bought at Window 12, the Railway Station, New York, or at the Brennan Station Window before boarding buses.

已知抛物线$y^2=2px\left(P>0\right)$上一点$M\left(1,m\right)\left(m>0\right)$到其焦点的距离为5，双曲线$\frac{x^2}{a}-y^2=1$的左顶点为A，若双曲线的一条渐近线与直线AM平行，则实数a的值是(   )